http://www.jbc.org/content/265/19/11083.full.pdf

Purification and characterization of a unique, potent, peptidyl probe for the high conductance calcium-activated potassium channel from venom of the scorpion Buthus tamulus.

A male accessory gland peptide that regulates reproductive behavior of female D. melanogaster

αB subunit of lens-specific protein α-crystallin is present in other ocular and non-ocular tissues

Cathelicidin LL-37 is one of the few human bactericidal peptides with potent antistaphylococcal activity. In this study we examined the susceptibility of LL-37 to proteolytic degradation by two major proteinases produced by Staphylococcus aureus, a metalloproteinase (aureolysin) and a glutamylendopeptidase (V8 protease). We found that aureolysin cleaved and inactivated LL-37 in a time- and concentration-dependent manner. Analysis of the generated fragments by mass spectroscopy revealed that the initial cleavage of LL-37 by aureolysin occurred between the Arg19-Ile20, Arg23-Ile24, and Leu31-Val32 peptide bonds, instantly annihilating the antibacterial activity of LL-37. In contrast, the V8 proteinase hydrolyzed efficiently only the Glu16-Phe17 peptide bond, rendering the C-terminal fragment refractory to further degradation. This fragment (termed LL-17-37) displayed antibacterial activity against S. aureus at a molar level similar to that of the full-length LL-37 peptide, indicating that the antibacterial activity of LL-37 resides in the C-terminal region. In keeping with LL-37 degradation by aureolysin, S. aureus strains that produce significant amounts of this metalloprotease were found to be less susceptible to LL-17-37 than strains expressing no aureolysin activity. Taken together, these data suggest that aureolysin production by S. aureus contributes to the resistance of this pathogen to the innate immune system of humans mediated by LL-37.

http://www.afrh.fr/web-content/documents/Basedocumentairemedicale/2004/4673.pdf

Degradation of Human Antimicrobial Peptide LL-37 by Staphylococcus aureus-Derived Proteinases

Horseradish peroxidase C dominates quantitatively among the isoperoxidases of horseradish root and has an isoelectric point close to 9. It consists of a hemin prosthetic group, 2 Ca2+ and 308 amino acid residues, including 4 disulfide bridges, in a single polypeptide chain that carries 8 neutral carbohydrate side-chains. The molecular weight of the polypeptide chain is 33890. Assuming an average carbohydrate composition of (GlcNAc)2, Man3, Fuc, Xyl for each carbohydrate chain, the molecular weight of native horseradish peroxidase C is close to 44 000. Cyanogen bromide fragments of reduced and carboxymethylated apo-peroxidase were purified by a combination of gel filtration and isoelectric focusing in urea, and cystine-containing tryptic fragments of apo-peroxidase were purified by gel filtration followed by disulfide cleavage and rechromatography at the initial conditions. The present paper discusses (a) isoelectric points and charge distribution within the native protein, the apoprotein and the cyanogen bromide fragments, (b) a buried pyrrolidonecarboxylyl amino terminus, (c) heterogeneity at the carboxyl terminus, and (d) a possible domain structure, likely from partial tryptic digestion.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1979.tb13061.x

Amino Acid Sequence Studies of Horseradish Peroxidase

Publisher Summary Proteolytic enzymes catalyzing the hydrolysis of peptide bonds involving exclusively the basic amino acid residues lysine and arginine have been available for many years. Trypsin is by far the best known enzyme exhibiting this high degree of specificity and, for that reason, it has played a central role in the studies of the primary structure of proteins. Recently, enzymes that specifically cleave peptide bonds at the carboxyl group of the acidic amino acid residues, aspartic acid and glutamic acid, have been discovered. One of these enzymes, staphylococcal protease, has this specificity and can be further restricted to glutamyl bonds only under certain controlled conditions. This enzyme can be used for the determination of the amino acid sequences of several proteins and proved to be another valuable tool for such studies. Staphylococcal protease shows a marked preference for certain aspartyl bonds when used in ammonium bicarbonate or acetate buffer. The staphylococcal protease is fully active in the presence of 0.2% sodium dodecyl sulfate and retains 50% of its activity in a 4 M urea solution. Digestion under these conditions could be attempted for proteins or peptides that are not readily attacked by the protease under nondenaturing conditions.

Cleavage at glutamic acid with staphylococcal protease.

Publisher Summary Staphylococci excretes extracellularly several types of proteins or enzymes, such as a variety of toxins, a nuclease, hyaluronidase, staphylokinase, lipase, and different proteases. This chapter is a study of one of the proteases which is of particular interest in view of its narrow and unique substrate specificity. The production of protease is carried out in a 28-liter fermentor, but substantial amounts of enzyme can be obtained even from 1 or 2 liters of medium. The strain V8 of Staphylococcus aureus is used in this assay as it is an excellent producer of the staphylococcal protease. The chapter further details the cultivation process. The chapter describes two assay methods: the first one is based on the method of Kunitz and is performed at either pH 4.0 with hemoglobin or at pH 7.8 with casein as substrates. The second method is based on the esterolytie activity of the protease. It further details the properties of the protease such as enzymic properties, physical properties and amino acid composition, activators and inhibitors and specificity.

Gabriel R. Drapeau

Papers

Cleavage at glutamic acid with staphylococcal protease.

[38] Protease from Staphyloccus aureus