MUSTI J SWAMY
Articles written in Journal of Biosciences
Volume 42 Issue 3 September 2017 pp 469-479 Article
The major protein of horse seminal plasma, HSP-1/2, exhibits membranolytic and chaperone-like activities and plays acrucial role in regulating sperm capacitation. L-Carnitine is a small polar molecule present in high concentrations inmammalian seminal plasma. The present results demonstrate that L-carnitine binds to HSP-1/2 and increases its thermalstability, enhances cooperativity of its chemical unfolding and decreases both chaperone-like and membranolytic activitiesof this protein. The HSP-1/2–L-carnitine complex exhibits anti-oxidative behaviour by inhibiting the production ofhydroxyl radicals, suggesting that it can protect other constituents of seminal plasma from damage by hydroxyl radicals. AsHSP-1/2 and L-carnitine share the same spatiotemporal location in the horse reproductive tract, this interaction is physiologicallysignificant and may prevent premature interaction of HSP-1/2 with sperm, which in turn regulates the spermcapacitation.
Volume 44 Issue 2 June 2019 Article ID 0035 Article
A Kunitz-type protease inhibitor (OPI, okra protease inhibitor) has been purified from okra (Abelmoschus esculentus) seedsby a combination of ammonium sulfate precipitation, anion-exchange chromatography and reverse-phase high-performanceliquid chromatography. The protein shows an apparent mass of 21 kDa on sodium dodecyl sulfate-polyacrylamide gelelectrophoresis under reducing condition. OPI exhibits inhibitory activity against trypsin. Analysis of the far-UV circulardichroism spectrum showed that the protein contains ~39% b-sheets but only ~5% a-helices. The protein is thermallyquite stable, and exhibits a cooperative thermal unfolding transition at ~70 deg C, as determined by circular dichroismspectroscopy and differential scanning fluorimetry. De novo sequencing of OPI by nanoESI-Q-ToF mass spectrometry (MS) allowed the assignment of about 83% of its primary structure, which indicated that the protein shares 43% sequence identitywith a putative 21 kDa trypsin inhibitor from Theobroma bicolor. An intramolecular disulfide linkage between Cys149 andCys156 was also detected. The protein showed ~24 and ~25% sequence identity with a-amylase/subtilisin inhibitor frombarley and soybean (Kunitz) trypsin inhibitor, respectively. Comparative structure modeling of OPI revealed a structuralfold similar to other Kunitz-type TIs. The presence of Cys149–Cys156 disulfide bond as detected by MS and a seconddisulfide bond connecting Cys44–Cys91, conserved in all Kunitz-type TIs, is also identified in the model.