The detection, quantification and partial characterisation of cathepsin B-like activity in human pathological synovial fluids

Irreversible inhibition of the bacterial cysteine protease-transpeptidase sortase (SrtA) by substrate-derived affinity labels

We report on the first synthesis, kinetic evaluation and application of novel substrate-derived inhibitors against the Staphylococcus aureus cysteine protease-transpeptidase, sortase (staphylococcal surface protein sorting A, SrtA). The peptidyl-diazomethane and peptidyl-chloromethane analogues, Cbz (benzyloxycarbonyl)-Leu-Pro-Ala-Thr-CHN(2) (I) and Cbz-Leu-Pro-Ala-Thr-CH(2)Cl (II) respectively were found to act as time-dependent irreversible inhibitors of recombinant sortase (SrtA(DeltaN)). The peptidyl-chloromethane analogue (II) was the most powerful with an inhibitor specificity constant (k(i)/K(i)) of 5.3x10(4) M(-1).min(-1), approx. 2-fold greater than that determined for the peptidyl-diazomethane (I). Additionally, using Western-blot analysis, we have been able to demonstrate that a biotinylated version of the peptidyl-diazomethane analogue, biotin-Ahx (aminohexanoyl)-Leu-Pro-Ala-Thr-CHN(2) (III), can be used as an affinity label to detect the presence of wild-type SrtA in crude cell lysates prepared from S. aureus.

The genes of the lysosomal cysteine proteinases cathepsin B, H, L, and S map to different mouse chromosomes

The mouse genes for the lysosomal cysteine proteinases cathepsin B, H, L, and S were mapped to Chromosomes (Chrs) 14, 9, 13, and 3, respectively. Two of the DNA probes used in this study detected an additional, independently segregating locus. The cathepsin B-specific probe hybridized to a locus on Chr 2, and the cathepsin H probe to a locus on the X Chr. These loci either correspond to pseudogenes or to cathepsin B- and cathepsin H-related genes. The four cysteine proteinases mapped in this study lie within known regions of conserved synteny between mouse and human chromosomes, when compared with the corresponding positions of their human homologs. Assuming that the genes of the cysteine proteinase gene family arose from a common ancestral gene, our results suggest that these four cysteine proteinases had been dispersed over different chromosomes before separation of mouse and human in evolution.