Purification and properties of an insecticidal metalloprotease produced by Photorhabdus luminescens strain 0805-P5G, the entomopathogenic nematode symbiont

An Overview of Ovarian Calyx Fluid Proteins of Toxoneuron nigriceps (Viereck) (Hymenoptera: Braconidae): An Integrated Transcriptomic and Proteomic Approach

The larval stages of the tobacco budworm, Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae), are parasitized by the endophagous parasitoid wasp, Toxoneuron nigriceps (Viereck) (Hymenoptera: Braconidae). During the injections of eggs, this parasitoid wasp also injects into the host body the secretion of the venom gland and the calyx fluid, which contains a polydnavirus (T. nigriceps BracoVirus: TnBV) and the Ovarian calyx fluid Proteins (OPs). The effects of the OPs on the host immune system have recently been described. In particular, it has been demonstrated that the OPs cause hemocytes to undergo a number of changes, such as cellular oxidative stress, actin cytoskeleton modifications, vacuolization, and the inhibition of hemocyte encapsulation capacity, which results in both a loss of hemocyte functionality and cell death. In this study, by using a combined transcriptomic and proteomic analysis, the main components of T. nigriceps ovarian calyx fluid proteins were identified and their possible role in the parasitic syndrome was discussed. This study provides useful information to support the analysis of the function of ovarian calyx fluid proteins, to better understand T. nigriceps parasitization success and for a more thorough understanding of the components of ovarian calyx fluid proteins and their potential function in combination with other parasitoid factors.

Purification and characterization of a metalloprotease produced by the C8 isolate of Serratia marcescens using silkworm pupae or casein as a protein source

Serratiopeptidase, a metalloprotease produced by Serratia marcescens, is produced through a fermentation process using carbohydrates and proteins as carbon and nitrogen sources. However, some byproducts of the silk industry could be an alternative source for serratiopeptidase production. Therefore, the present work is focused on the purification and characterization of a serratiopeptidase produced from the C8 isolate of Serratia marcescens and obtained from a Colombian silkworm hybrid using casein or silkworm pupae. The protease was purified using ultrafiltration, anion-exchange, and size-exclusion chromatography. The purified enzyme showed a molecular weight of ~50 kDa with a purity above 96%, an isoelectric point of ~4.6, optimum pH and temperature of 6 and 50 °C, and stability at 4 °C for one month. The kinetic constants using azocasein as substrate were 0.63 mM (K_m), 2,016 μM/min (V_max), 41.41 s^-1 (K_cat), and 6.56 × 10⁷ M^-1 s^-1 (K_cat/K_m). Inhibition by 5 mM EDTA or 1,10-phenanthroline was recovered by adding Zn²⁺ at the same concentration. Mass spectrometry analysis indicated 94% homology with the sequence of serratiopeptidase produced by the E-15 strain. We purified and characterized a serratiopeptidase produced by the C8 isolate of S. marcescens in a culture medium based on a renewable source from the silk industry.