Site-specific PEGylation of recombinant lysostaphin / 生物工程学报

Lysostaphin (Lysn) is an antibacterial metalloendopeptidase that cleaves the pentaglycin bridges in the cell wall of Staphylococci. Although many studies have demonstrated its high activity in vitro, the medical application of Lysn has been hampered by its short half-life in vivo. In order to enhance its stability in vivo without significantly suppressing the enzymatic activity, we designed and tested eight single cysteine substitutions in Lysn for covalent attachment of polyethylene glycol chains (PEGylation). The purified mutants, fully reduced by Dithiothreitol (DTT), were treated with mPEG-MAL(20 kDa). The PEG modification efficiency was above 70% as determined by reverse-phase high-pressure liquid chromatography (HPLC) analysis. The PEG-Lysn proteins were further purified by cation exchange chromatography (MacroCap SP), reaching at least 95% purity. The activities of the PEG-Lysn proteins were determined by the turbidity and minimum inhibitory concentration (MIC) assays. We found that the PEGylated V240C and T244C mutants retained about 50% of the original antibacterial activity of Lysn. Overall, this study will help develop highly stable and active PEG-Lysn to treat systemic S. aureus infections.

Quantitative specific detection of Staphylococcus aureus based on recombinant lysostaphin and ATP bioluminescence / 生物工程学报

Quantitative specific detection of Staphylococcus aureus is based on recombinant lysostaphin and ATP bioluminescence. To produce recombinant lysostaphin, the lysostaphin gene was chemically synthesized and inserted it into prokaryotic expression vector pQE30, and the resulting expression plasmid pQE30-Lys was transformed into E. coli M15 for expressing lysostaphin with IPTG induction. The recombinant protein was purified by Ni(2+)-NTA affinity chromatography. Staphylococcus aureus was detected by the recombinant lysostaphin with ATP bioluminescence, and plate count method. The results of the two methods were compared. The recombinant lysostaphin was successfully expressed, and a method of quantitative specific detection of S. aureus has been established, which showed a significant linear correlation with the colony counting. The detection method developed has good perspective to quantify S. aureus.

Controlled release by novel lysostaphin-loaded hydroxyapatite/chitosan composites / 药学学报

Lysostaphin is highly effective on eliminating methicillin resistant Staphylococcus aureus (MRSA). In order to achieve controlled release of lysostaphin, a biocompatible drug carrier is needed. Hydroxyapatite/chitosan (HA/CS) composites were chosen to carry lysostaphin and sample composites with different weight ratios of HA to CS, including 80/20, 70/30, 60/40, and 40/60, were prepared. Multiple analyses were performed to determine the structural and physicochemical properties of the composites, including scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. We immersed HA/CS composites loaded with 1 wt% lysostaphin to test in vitro release activity and cultured MC3T3-E1 cells to carry out biocompatibility test. The result of the release behavior of the composites revealed that the controlled release of lysostaphin from 60/40 HA/CS composites was the highest release rate of (87.4 ± 2.8)%, which lasted for 120 hours. In biocompatibility testing, MC3T3-E1 cells were able to proliferate on the surface of these composites, and the extract liquid from the composites could increase the growth of the cells. These results demonstrate the controlled release of lysostaphin from HA/CS composites and their biocompatibility, suggesting the potential application of these composites to bone injury and infection applications.

Site-directed mutagenesis and sulfhydryl PEGylation of lysostaphin / 生物工程学报

The purpose of this paper is to establish sulfhydryl site-directed PEGylation method for lysostaphin and to evaluate effects of mutagenesis and modification of amino acid residue within putative linker on enzyme activity. On the basis of structural analysis of lysostaphin, amino acid 133-154 of tentative linker between the N-terminal and C-terminal domain were chosen as the candidate residues for site-directed mutagenesis to cysteine. Subsequently, sulfhydryl site-directed PEGylation was performed by reacting PEG-maleimide reagent with the newly introduced cysteine residue of the mutant lysostaphin. The Cys-mutant and PEG-modified proteins were both purified, and their enzymatic activity were further PEGylated lysostaphins. The mono-PEGylated lysostaphins were separated from unmodified lysostaphins through highly efficient one step method with Ni(2+)-NTA column chromatography. However, both Cys-mutant and PEGylated lysostaphin only retained partial activities of the wild-type enzyme. It suggests that sulfhydryl site-directed PEGylation modification of the tentative linker between the N-terminal and C-terminal domain may affect the catalytic activity of lysostaphin.

Purification of recombinant lysostaphin by monoclonal antibody affinity chromatography / 生物工程学报

Lysostaphin, a specific endopeptidase enzyme derived from Staphylococcus aureus, is a bactericidal agent against Staphylococcus and difficult to be drug-resistant. This study established the monoclonal antibody affinity chromatography to obtain lysostaphin of high purity for drug-use standard. The purified Lysostaphin was of > 95% purity and its recovery rate more than 90%. Moreover, the affinity column kept its efficiency of purification invariable after more than 30 times repeat. Also, the dye release assay validated that the purified lysostaphin had significant bactericidal activity. This method was simple and of high efficacy for the lysostaphin purification and showed its potency in commercial production.

Detection of recombinant lysostaphin using antibody sandwish enzyme-linked immunoadsorbent assay / 生物工程学报

The double-antibody-sandwich enzyme-linked immunoadsorbent assay (ELISA) for detection of rLysostaphin in humans had been developed and established through this study. rLysostaphin of high purity ( > 95 % ) produced in Shanghai Hi-Tech United Bio-Technological Research & Development Co., Ltd (SHUBRD) was used to produce a rabbit anti-rLysostaphin polyclonal antibody. The standard curve of rLysostaphin polyclonal antibody that was constructed showed that the lowest range of detection was found at 0. 98 ng of rLysostaphin/mL, and the curve exhibited linearity preferably from 0. 98 to 500 ng of rLysostaphin/mL. When three serum samples of the same batch were assayed for 6 replicates, and more 3 samples from different batches for 6 replicates, the average intra-assay and inter-assay coefficient variances ( CV) were 6. 4% and 6. 5%, respectively. The relative recovery rate was 98.6% when quantitative standard antigens were added to the serum. The present method for detection of rLysostaphin in serum is specific, highly sensitive, highly precise, and exhibited a low CV and will be helpful in the further study of rLysostaphin pharmacokinetics and holds promise in clinical applications.

Nuevas pruebas bioquímicas para identificación del género Staphylococcus / New biochemical tests for identification of Staphylococcus genus

Se han aislado 60 cepas del género Staphylococcus en el hospital Guillermo Almenara Irigoyen de secreciones de cátetes y urocultivos, los cuales fueron clasificdas siguiendo los lineamientos del esquema de KLOOS y Schcleides y el manual de Bergey identificandose a las siguientes especies: S.aureus (68.3 por ciento). s. saprolyticus (13.3 por ciento). s. epidermis (83 por ciento). S. Haemolyticus (5.0 por ciento), S.simulans (5.0 por ciento). En base al esquema de KLOOS y COL y combinando algunos caracteres fenotipicos esenciales con caracteres con caracteres secundarios se desarrolló un esquema simplificado de 4 pruebas bioquímicos: Determinación de la enzima coagulasa, sensibilidad o resistencia a la Lisostofina, prueba de termonucleasa y sensibilidad o resistencia a 5 ug de novabiocina, habiéndose encontrado 2 biovaves en S. aureus y S. epidermis, con resultados variables en la prueba de termonucleasa y coagulasa. s. saprophyticus, s. simulans, s. haemolyticus dieron resultados coincidentes con el esquema de KLOOS.