Structural characterization reveals the keratinolytic activity of an arthrobacter nicotinovorans protease.

Elevated cadmium (Cd) concentrations in fishery byproducts are an environmental concern, that might be reduced by enzymatic removal and adsorption of the contaminants during recycling the byproducts as animal food. We cloned the gene for Arthrobacter nicotinovorans serine protease (ANISEP), which was isolated from the hepatopancreas of the Japanese scallop (Patiopecten yessoensis) and has been found to be an effective enzyme for Cd(II) removal. The gene is 993 bp in length and encodes 330 amino acids, including the pre (1-30) and pro (31-111) sequences. The catalytic triad consists of His, Asp, and Ser. Sequence similarities indicate that ANISEP is a extracellular serine protease. X-ray crystallography revealed structural similarities between ANISEP and the trypsin-like serine protease NAALP from Nesterenkonia sp. Site-directed mutagenesis identified Ser171 as catalytic residue. The keratinolytic activity of ANISEP was 10-fold greater than that of trypsin. ANISEP digested Cd(II)-bound recombinant metallothionein MT-10a from Laternula elliptica, but did not release Cd. These results further suggest ANISEP is a trypsin-like serine protease that can release Cd from the Japanese scallop hepatopancreas because of its strong keratinolytic activity.

Angiogenin expression in the sera and skin of patients with rheumatic diseases.

Vascular abnormalities are one of the common features in rheumatic diseases, but their pathogenesis is still not known. Angiogenin, a molecule implicated in the angiogenic process, may play some roles in such vascular changes. Serum angiogenin concentrations were measured in 21 scleroderma patients, 10 patients with systemic lupus erythematosus (SLE), 21 patients with dermatomyositis (DM), 5 patients with polymyositis (PM), 11 patients with clinically amyopathic DM (CADM) and 12 normal subjects, with specific enzyme-linked immunosorbent assays. Angiogenin mRNA in vivo was determined in skin tissues of 5 DM patients, 4 CADM patients, 5 SLE patients and 7 normal subjects using quantitative real-time polymerase chain reactions. We could not find any significant differences in the serum angiogenin levels among normal subjects and patients with rheumatic diseases. However, when we evaluated the correlation of serum angiogenin levels with clinical features of 32 DM/CADM patients, the patients with increased angiogenin levels had significantly higher aldolase levels than those with decreased levels. On the other hand, angiogenin mRNA is significantly up-regulated in the involved skin of DM and CADM, suggesting that angiogenin expression is up-regulated locally in the skin but not in sera of patients with DM and CADM. In conclusion, dysregulated angiogenin expression may contribute to the pathogenesis of myositis as well as skin involvement via the vascular change in DM/CADM. Further studies with an increased number of patients may help to clarify the relationship between angiogenin and vascular abnormalities in rheumatic diseases and to develop new therapeutic strategies.