Metallopeptide compound, preparation method and application thereof

Abstract

The application discloses a metal polypeptide compound and a preparation method and application thereof. The preparation method of the metal polypeptide compound provided by the application comprises the following steps: obtaining RLRGG-PPh2 by condensation reaction of polypeptide RLRGG and 3-(diphenylphosphino)propionic acid; and obtaining RLRGG-PPh2Au by reaction of RLRGG-PPh2 and chloro(dimethylsulfide)gold (I). The metal polypeptide compound provided by the application not only retains the inhibitory activity of gold (I) complex on viral protease, but also utilizes the targeted delivery characteristics of RLRGG polypeptide, improves the effective action probability of the metal active center at the key action site of the virus, and realizes the synergistic inhibition on the viral replication process. Experimental results show that the metal polypeptide can effectively reduce the viral infection level, and inhibit the viral replication activity through multi-target action and multi-regulation mechanism.

Description

Technical Field

[0001] This invention belongs to the field of polypeptide drug technology, and particularly relates to a metal polypeptide compound, its preparation method and application. Background Technology

[0002] Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a single-stranded RNA virus belonging to the β-coronavirus genus. The continued spread and evolution of the virus makes antiviral drug development a hot topic and a challenge in the pharmaceutical field. Papain-like protease protein (PLpro) plays an important role in promoting viral replication and evading immune regulation, making it a potential antiviral target. However, there is currently a lack of antiviral drugs targeting PLpro in clinical practice. This is partly due to the lack of drug design strategies targeting the multiple biological functions of PLpro, and partly because PLpro exhibits structural drift in different coronaviruses and has various binding forms with other proteins in vivo, making it easy for potential drug molecules to lose specificity and selectivity towards PLpro. Metal-based drugs are a new class of broad-spectrum antiviral agents that can inhibit viral replication by disrupting the key zinc finger structure in PLpro. However, metal-based drugs have drawbacks such as weak targeting and significant side effects, thus necessitating the development of novel metal-based antiviral drugs.

[0003] Metallic drugs, as a class of bioactive molecules with unique mechanisms of action, have gradually attracted attention in the field of antiviral research. Studies have shown that gold (I) compounds can inhibit the catalytic activity of viral proteases by forming stable gold-sulfur coordination bonds with the thiol groups of cysteine ​​residues in proteins. PLpro contains a zinc finger domain closely related to its structural stability and function; this structure relies on the coordination of zinc ions with cysteine ​​residues to maintain its integrity. As a soft acid metal, gold (I) ions have a higher affinity for sulfur atoms and can disrupt the zinc finger structure of PLpro through metal substitution, thereby causing conformational changes in the protein and causing it to lose its substrate recognition and catalytic abilities. Mechanistically, this suggests the potential to inhibit viral replication and modulate the immune system.

[0004] Although metal-based drugs have clear advantages in inhibiting PLpro, existing metal-based drugs generally suffer from weak targeting, uncontrollable biodistribution, and significant potential toxic side effects, limiting their further application. Therefore, it is necessary to improve the selectivity of metal active sites for PLpro through rational molecular design, thereby reducing the risk of nonspecific effects while maintaining inhibitory activity.

[0005] Peptide molecules have certain advantages in the design of viral protease inhibitors due to their ability to mimic natural protein-protein interaction interfaces. PLpro exhibits a clear recognition preference for specific substrate sequences, and related short peptide sequences can serve as its binding or recognition fragments. Combining the active metal site with a peptide structure capable of recognizing PLpro holds promise for targeted delivery of metal drugs, thereby improving their inhibitory selectivity against PLpro. However, existing metal-peptide systems mostly employ non-covalent or structurally unstable linkages, making them prone to dissociation or inactivation in complex physiological environments. This hinders effective regulation of metal activity and remains insufficient to meet the demands of antiviral applications.

[0006] Therefore, there is an urgent need to develop a novel metal peptide antiviral drug system that is structurally stable, has a clear target, and can synergistically inhibit the enzymatic activity and immunomodulatory function of PLpro, in order to overcome the shortcomings of existing technologies and provide new treatment methods for SARS-CoV-2 and its variants. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a structurally stable, specifically targeted metal-peptide compound capable of synergistically inhibiting PLpro enzymatic activity and its immunomodulatory function, along with its preparation method and applications. The metal-peptide compound provided by this invention can effectively inhibit SARS-CoV-2 virus infection and immune interference.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides a metal polypeptide compound with the chemical structure shown in Formula I: .

[0009] In another aspect, the present invention provides a method for preparing the above-mentioned metal polypeptide compound, comprising the following steps: (1) The polypeptide RLRGG was condensed with 3-(diphenylphosphaneyl)propanoic acid to obtain intermediate 1 RLRGG-PPh2; The chemical structure of the polypeptide RLRGG is shown in Formula II; the chemical structure of the 3-(diphenylphosphino)propionic acid is shown in Formula III; and the chemical structure of intermediate 1 RLRGG-PPh2 is shown in Formula IV. ; ; .

[0010] In a preferred embodiment, the condensation reaction specifically involves condensing the polypeptide RLRGG and 3-(diphenylphosphino)propionic acid in a solvent containing 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) and 4-dimethylaminopyridine (DMAP).

[0011] Preferably, the molar ratio of the polypeptide RLRGG to 3-(diphenylphosphino)propionic acid is 1:1-1.2.

[0012] And / or, the molar ratio of the polypeptide RLRGG to EDC·HCl and DMAP is 1-1.5:1.

[0013] And / or, the solvent is a mixture of acetonitrile (ACN) and water or a mixture of tetrahydrofuran (THF) and water.

[0014] And / or, the condensation reaction takes 20-24 h.

[0015] In some specific embodiments, the condensation reaction is followed by water quenching, reversed-phase chromatography separation and purification, and lyophilization.

[0016] And / or, the polypeptide RLRGG is prepared by solid-phase synthesis.

[0017] (2) The intermediate 1 RLRGG-PPh2 was reacted with Chloro(dimethylsulfide)gold(I), (CH3)2SAuCl to obtain the metal polypeptide compound RLRGG-PPh2Au.

[0018] In a preferred embodiment, the reaction is carried out in a solvent.

[0019] Preferably, the solvent is a mixture of acetonitrile (ACN) and water or a mixture of tetrahydrofuran (THF) and water.

[0020] And / or, the molar ratio of the intermediate 1 RLRGG-PPh2 to gold(I) chloride (dimethyl sulfide) is 1:1-1.1.

[0021] And / or, the temperature of the reaction is 0-4°C.

[0022] And / or, the reaction time is 5-7 h.

[0023] In some specific embodiments, intermediate 1 RLRGG-PPh2 is stirred in a solvent at 0-4°C for 10 minutes before (CH3)2SAuCl is added to carry out the reaction; the purpose of low-temperature stirring is to keep intermediate 1 in a low-temperature environment to avoid the inability to react after directly adding (CH3)2SAuCl.

[0024] In some specific embodiments, the reaction includes post-processing such as reversed-phase chromatography separation and purification, and lyophilization.

[0025] In another aspect, the present invention provides the use of the above-mentioned metal polypeptide compound in the preparation of medicaments for treating and / or preventing novel coronavirus infection.

[0026] Preferably, its application in inhibiting the activity of papain-like protease of the novel coronavirus.

[0027] In another aspect, the present invention provides the application of the above-mentioned metal polypeptide compound in the preparation of papain-like protease inhibitors.

[0028] Preferably, its application in the preparation of papain-like protease inhibitors for the novel coronavirus.

[0029] In the technical solution of this invention, the novel coronavirus includes SARS-CoV-2 virus and its mutant strains, SARS-CoV-1 virus, and MERS-CoV virus. The SARS-CoV-2 virus mutant strain includes Omicron XBB.1.5.

[0030] This invention has the following advantages and beneficial effects: This invention covalently binds the PLpro-recognizing peptide RLRGG to a diphenylphosphine gold (I) complex. This allows the peptide backbone to perform targeted recognition while simultaneously guiding the gold (I) active site to act on PLpro, a key protein in viral replication, thereby enhancing the inhibitory selectivity of the metal-peptide against this target. The metal-peptide compound retains the inhibitory activity of the gold (I) complex against viral proteases, and utilizes the targeted delivery characteristics of the RLRGG peptide to increase the probability of effective action of the metal active site at key viral sites, achieving synergistic inhibition of viral replication. Experimental results show that this metal-peptide compound can effectively reduce viral infection levels and inhibit viral replication activity through multi-target action and multiple regulatory mechanisms.

[0031] The metallopeptide compounds provided by this invention exhibit low cytotoxicity, with a half-maximal cytotoxic concentration (CMC). 50The half-maximal inhibitory concentration (IC50) was 334.0 μM. The metallopeptide compound provided by this invention exhibits good inhibitory effects on PLpro, a key protease for the replication of SARS-CoV-2 virus and its mutant strain OmicronXBB.1.5, SARS-CoV-1 virus, and MERS-CoV virus, with an IC50 concentration of 334.0 μM. 50 The concentrations were 0.540 μM, 1.198 μM, and 1.592 μM, respectively. and 17.79 μM.

[0032] The metal polypeptide compound provided by this invention has an Au / polypeptide molar ratio of approximately 1, and the gold loading exhibits a controllable increasing trend.

[0033] The metal polypeptide compound provided by this invention has a higher intracellular gold loading capacity compared to metal complexes without bound polypeptides.

[0034] The metal polypeptide compound provided by this invention does not compromise the overall conformational stability of the polypeptide upon the introduction of Au.

[0035] The metal polypeptide compound provided by this invention, when bound to SARS-CoV-2 PLpro, did not cause significant changes in the overall secondary structure of PLpro, and no obvious protein defolding or instability was observed. Attached Figure Description

[0036] Figure 1 This is a high-resolution mass spectrum of the metal polypeptide compound RLRGG-PPh2Au in Example 1 of this invention.

[0037] Figure 2 This is a graph showing the cytotoxicity test results of the metal polypeptide compound RLRGG-PPh2Au in Example 2 of this invention.

[0038] Figure 3 This is a graph showing the inhibition rate test results of the metal polypeptide compound in Example 2 of this invention against SARS-CoV-2 PLpro at different concentrations.

[0039] Figure 4 This is a graph showing the inhibition rate test results of the metal polypeptide compound in Example 2 of the present invention against Omicron XBB.1.5PLpro at different concentrations.

[0040] Figure 5 This is a graph showing the test results of the inhibition rate of the metal polypeptide compound in Example 2 of the present invention against SARS-CoV-1 PLpro at different concentrations.

[0041] Figure 6 This is a graph showing the inhibition rate test results of the metal polypeptide compound in Example 2 of this invention against MERS-CoV PLpro at different concentrations.

[0042] Figure 7 This is a graph showing the gold content test results of the metal polypeptide compound in Example 2 of the present invention.

[0043] Figure 8 This is a graph showing the results of intracellular gold loading tests of the metal polypeptide compound at different concentrations in Example 2 of the present invention.

[0044] Figure 9 This is a graph showing the conformational stability analysis results of the metal polypeptide compound in Example 2 of this invention at different concentrations.

[0045] Figure 10 This is a graph showing the conformational change analysis results of the metal polypeptide compound in Example 2 of this invention after binding with SARS-CoV-2 PLpro at different concentrations. Detailed Implementation

[0046] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0047] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0048] Example 1: This embodiment provides a metal polypeptide compound RLRGG-PPh2Au, the synthesis process of which is as follows: (1) Solid-phase synthesis of RLRGG: Fmoc-Gly-Wang resin was selected as the solid support with a loading of 0.60 mmol / g; 2.0 g of the above resin was weighed and placed in a reaction column; anhydrous N,N-dimethylformamide (DMF) was added to the reaction column to fully swell the resin, and the mixture was shaken at room temperature for 30 min, after which the solvent was removed; 20% (v / v) piperidine / DMF solution was added to the swollen resin, and the reaction was carried out at room temperature for 10 min. After deprotection, the process was repeated once to completely remove the N-terminal Fmoc protecting group. After deprotection, the resin was washed with DMF (3 times) and dichloromethane (DCM, 2 times) to remove residual piperidine and byproducts. The pentapeptide was synthesized by stepwise extension from the C-terminus to the N-terminus, with the target sequence being Arg–Leu–Arg–Gly–Gly (RLRGG). After the pentapeptide sequence was fully constructed, the resin was transferred to a cleavage reaction vessel for cleavage of the peptide from the resin and removal of the side chain protecting group. After the reaction, the cleavage solution was filtered and collected, and slowly added dropwise to an excess of cold anhydrous diethyl ether to precipitate the crude peptide. The precipitate was centrifuged, washed twice with cold anhydrous diethyl ether, and then dried under vacuum to obtain crude RLRGG pentapeptide. The crude product was purified by reversed-phase high-performance liquid chromatography (RP-HPLC), and the fraction corresponding to the target peak was collected and freeze-dried to obtain approximately 1 g of white or off-white solid product.

[0049] (2) Synthesis of intermediate 1: RLRGG (179 μmol, 100 mg), 3-(diphenylphosphaneyl)propanoic acid (215 μmol, 56 mg), EDCl·HCl (269 μmol, 52 mg), DMAP (179 μmol, 22 mg), ACN (2 mL) and deionized water (2 mL) were added to a 50 mL ground glass reaction tube. The mixture was stirred at 25 °C for 24 h. The reaction was quenched with an equal amount of water. The mixture was separated and purified by reversed-phase chromatography and then freeze-dried at -80 °C to obtain a white powder (125.1 mg, yield 84%).

[0050] The reaction process in step (2) is shown below:

[0051] (3) Synthesis of RLRGG-PPh2Au: In a 50 mL ground glass joint reaction tube, intermediate 1 (137 μmol, 100 mg), ACN (2 mL) and deionized water (2 mL) were added and stirred at 4 °C for 10 min; then (CH3)2SAuCl (151 μmol, 44 mg) was added; the reaction was stirred at 4 °C for 7 h; after the reaction was completed, the product was separated and purified by reversed phase chromatography, and then lyophilized at -80 °C to obtain a pale yellow powder (107.2 mg, yield 76%).

[0052] The reaction process in step (3) is shown below:

[0053] Figure 1 The high-resolution mass spectrum of RLRGG-PPh2Au obtained in step (3) of this embodiment is as follows: ESI-MS(+)[m / z]: 1030.3503 [M+H] + 994.3736 [M-Cl] + 515.6793 [M+2H] 2+ 497.6905 [M-Cl+H] 2+ .

[0054] Example 2: This embodiment experimentally tested the performance of RLRGG-PPh2Au in Example 1, as detailed below: 1. Experimental Methods (1) Cytotoxicity of RLRGG-PPh2Au to VeroE6 cells: The compound was serially diluted with MEM medium to final concentrations of 4000 μM, 2000 μM, 1000 μM, 700 μM, 600 μM, 500 μM, 400 μM, 300 μM, 200 μM, 100 μM, 50 μM, and 25 μM. 100 μL of each of the above different concentrations of the test sample was added to a 96-well plate containing VeroE6 cells, in six copies. The plates were incubated for 24 hours. Cell viability was then tested using CCK8 reagent, and the fluorescence value at 450 nm was measured.

[0055] (2) Inhibitory effect of RLRGG-PPh2Au on SARS-CoV-2 PLpro activity: In this embodiment, the inhibitory effect of RLRGG-PPh2Au on SARS-CoV-2 PLpro protease was studied by enzyme-catalyzed fluorescence energy resonance transfer (FRET) experiment. Z-RLRGG-AMC was used as the fluorescent substrate. PLpro can cleave the fluorescent substrate to release AMC and emit fluorescence. Therefore, different concentration gradients of the test compounds were incubated with PLpro, and the fluorescence values ​​at excitation / emission = 355 nm / 460 nm were measured, which can be used to calculate the IC50 of each compound. 50 The specific steps are as follows: Weigh out RLRGG-PPh2Au and prepare a 10 mM stock solution with PBS buffer. Then, serially dilute with DMSO to final concentrations of 5 μM, 4 μM, 3 μM, 2 μM, 1 μM, 0.6 μM, 0.5 μM, 0.4 μM, 0.3 μM, 0.2 μM, and 0.1 μM for the test samples. Add 25 μL of each test sample solution to a 96-well plate, four times. Then, add SARS-CoV-2 PLpro protein solution (final concentration 125 nM) to each well, vortex thoroughly to mix, and incubate for 30 minutes. Finally, add fluorescent substrate to each well to a final concentration of 100 μM to initiate the reaction.

[0056] (3) Inhibitory effect of RLRGG-PPh2Au on the activity of Omicron XBB.1.5 PLpro: In this example, the inhibitory effect of RLRGG-PPh2Au on Omicron XBB.1.5 PLpro was studied by enzyme-catalyzed fluorescence energy resonance transfer (FRET) experiment. The method was the same as above, except that the final concentrations of RLRGG-PPh2Au were 16 μM, 8 μM, 7 μM, 2.5 μM, 1.8 μM, 0.6 μM, 0.625 μM, 0.3125 μM, 0.2 μM, 0.15 μM, 0.1 μM and 0.05 μM.

[0057] (4) Inhibitory effect of RLRGG-PPh2Au on SARS-CoV-1 PLpro: In this example, the inhibitory effect of RLRGG-PPh2Au on SARS-CoV-1 PLpro was studied by enzyme-catalyzed fluorescence energy resonance transfer (FRET) experiment. The method was the same as above, except that the final concentrations of RLRGG-PPh2Au were 200 μM, 100 μM, 35 μM, 8 μM, 7 μM, 6 μM, 3 μM, 0.375 μM, 0.188 μM, 0.094 μM, 0.047 μM, and 0.0235 μM, respectively.

[0058] (5) Inhibitory effect of RLRGG-PPh2Au on MERS-CoV PLpro: In this example, the inhibitory effect of RLRGG-PPh2Au on MERS-CoV PLpro was studied by enzyme-catalyzed fluorescence energy resonance transfer (FRET) experiment. The method was the same as above, except that the final concentrations of RLRGG-PPh2Au were 100 μM, 50 μM, 40 μM, 30 μM, 20 μM, 15 μM, 10 μM, 8 μM, 2 μM and 1 μM.

[0059] (6) Gold content of RLRGG-PPh2Au: The gold content was determined by inductively coupled plasma mass spectrometry (ICP-MS). After the compound was nitrated with 50% nitric acid at 80°C for 6 hours, the metal content was determined by ICP-MS. The molar ratio of Au to RLRGG-PPh2Au was analyzed.

[0060] (7) Analysis of gold loading in VeroE6 cells using RLRGG-PPh2Au: To further evaluate the cellular uptake capacity of the compound, VeroE6 cells were co-incubated with RLRGG-PPh2Au at concentrations of 6 μM, 12 μM, and 24 μM for 16 hours. Subsequently, the cell samples were nitrated in 60% nitric acid at 80°C for 6 hours, and the intracellular metal content was determined by ICP-MS.

[0061] (8) Conformational stability analysis of RLRGG-PPh2Au: The secondary structural characteristics of RLRGG and RLRGG-PPh2Au were systematically analyzed by circular dichroism (CD). The experiment was conducted at two concentrations of 50 μM and 100 μM to eliminate the interference of concentration effect on conformational determination.

[0062] (9) Conformational changes of RLRGG-PPh2Au after binding with SARS-CoV-2 PLpro: The compound was diluted to a final concentration of 50 μM and 100 μM, respectively, and incubated with SARS-CoV-2 PLpro at a concentration of 1 mg / mL for 24 hours. Then, RLRGG-PPh2Au that was not bound to PLpro in the test sample was removed by ultrafiltration using a 10 kDa ultrafiltration tube. CD detection and circular dichroism analysis were performed, and the proportion of its secondary structure composition was further calculated.

[0063] 2. Experimental Results (1) Figure 2This presents the toxicity test results of RLRGG-PPh2Au at different concentrations on VeroE6 cells. Specifically, after co-incubating the two compounds for 24 hours, cell viability was assessed using the CCK-8 assay. The results showed that the compound exhibited low toxicity to VeroE6 cells, with a CCK-8 concentration of [missing information]. 50 = 334.0 μM.

[0064] (2) Figure 3 The inhibition rate of RLRGG-PPh2Au against SRAS-CoV-2 PLpro at different concentrations was measured. Compared with the unmodified RLRGG control group, the compound at concentrations above 3 μM achieved complete inhibition of SRAS-CoV-2 PLpro activity. The inhibitory activity was dose-dependent, and its IC50 value was [not specified]. 50 = 0.540 μM.

[0065] (3) Figure 4 The inhibition rate of RLRGG-PPh2Au on Omicron XBB.1.5 PLpro at different concentrations was measured. Compared with the unmodified RLRGG control group, the compound at concentrations above 8 μM achieved complete inhibition of Omicron XBB.1.5 PLpro activity. The inhibitory activity was dose-dependent, and its IC50 value was [not specified]. 50 = 1.198 μM.

[0066] (4) Figure 5 The inhibition rate of RLRGG-PPh2Au against SRAS-CoV-1 PLpro at different concentrations was measured. Compared with the unmodified RLRGG control group, the compound at concentrations above 8 μM achieved complete inhibition of SRAS-CoV-1 PLpro activity. The inhibitory activity was dose-dependent, and its IC50 value was [not specified]. 50 = 1.592 μM.

[0067] (5) Figure 6 The inhibition rate of RLRGG-PPh2Au against MERS-CoV PLpro at different concentrations was measured. Compared with the unmodified RLRGG control group, the compound at concentrations above 40 μM achieved complete inhibition of MERS-CoV PLpro activity. The inhibitory activity was dose-dependent, and its IC50 value was [not specified]. 50 = 17.79 μM.

[0068] (6) Figure 7 The gold content analysis of RLRGG-PPh2Au showed that, compared with the unmodified RLRGG control group, the Au content in RLRGG-PPh2Au was significantly increased, the molar ratio of Au / RLRGG-PPh2Au was 1, and the gold loading showed an adjustable increasing trend.

[0069] (7) Figure 8 The results show the intracellular gold loading of RLRGG-PPh2Au at different concentrations. Compared with the metal complex alone, RLRGG-PPh2Au significantly enhanced the ability of gold to enter cells, and the intracellular gold loading showed a dose-dependent increasing trend with increasing treatment concentration. The preparation process of the metal complex alone was the same as in Example 1, except that the peptide RLRGG was not used; instead, 3-(diphenylphosphine)propionic acid was directly reacted with (CH3)2SAuCl.

[0070] (8) Figure 9 The results are the conformational stability analysis results of RLRGG-PPh2Au at different concentrations. Neither the compound nor the unmodified RLRGG control group showed typical α-helix or β-sheet characteristic signals. The CD spectrum showed random coil conformation characteristics.

[0071] (9) Figure 10 The conformational changes of RLRGG-PPh2Au after binding with SARS-CoV-2 PLpro at different concentrations are shown: the binding did not cause significant changes in the overall secondary structure of PLpro, and no obvious protein unfolding or instability was observed, which indicates that the interaction between the metallopeptide and PLpro is more likely to occur in local regions. Figure 10 In this context, eq represents equivalent.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A metal polypeptide compound, characterized in that, The chemical structure of the metal polypeptide compound is shown in Formula I: 。 2. The method for preparing the metal polypeptide compound according to claim 1, characterized in that, Includes the following steps: (1) The polypeptide RLRGG was reacted with 3-(diphenylphosphino)propionic acid to obtain intermediate 1 RLRGG-PPh2; The chemical structure of the polypeptide RLRGG is shown in Formula II; the chemical structure of the 3-(diphenylphosphino)propionic acid is shown in Formula III; and the chemical structure of intermediate 1 RLRGG-PPh2 is shown in Formula IV. ； ； ； (2) The intermediate 1 RLRGG-PPh2 was reacted with gold(dimethylsulfide) chloride (I) to obtain the metal polypeptide compound RLRGG-PPh2Au.

3. The preparation method according to claim 2, characterized in that, In step (1), the condensation reaction specifically involves condensing the polypeptide RLRGG and 3-(diphenylphosphino)propionic acid in a solvent containing 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) and 4-dimethylaminopyridine (DMAP).

4. The preparation method according to claim 3, characterized in that, In step (1), the molar ratio of the polypeptide RLRGG to 3-(diphenylphosphino)propionic acid is 1:1-1.2; And / or, in step (1), the molar ratio of the polypeptide RLRGG to EDC·HCl and DMAP is 1-1.5:1; And / or, in step (1), the solvent is a mixture of acetonitrile and water or a mixture of tetrahydrofuran and water; And / or, in step (1), the condensation reaction takes 20-24 h; And / or, in step (1), the polypeptide RLRGG is prepared by solid-phase synthesis.

5. The preparation method according to claim 3, characterized in that, In step (2), the reaction is carried out in a solvent.

6. The preparation method according to claim 5, characterized in that, In step (2), the solvent is a mixture of acetonitrile and water or a mixture of tetrahydrofuran and water; And / or, in step (2), the molar ratio of intermediate 1 RLRGG-PPh2 to gold(I) chloride (dimethyl sulfide) is 1:1-1.1; And / or, in step (2), the temperature of the reaction is 0-4°C; And / or, in step (2), the reaction time is 5-7 h.

7. The use of the metal polypeptide compound of claim 1 in the preparation of medicaments for treating and / or preventing novel coronavirus infection.

8. The application according to claim 7, characterized in that, Application in inhibiting the activity of papain-like protease in the novel coronavirus.

9. The use of the metal polypeptide compound of claim 1 in the preparation of papain-like protease inhibitors.

10. The application according to claim 9, characterized in that, Application in the preparation of papain-like protease inhibitors for the novel coronavirus.

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