Keiko Ochiai

MS-271, a novel inhibitor of calmodulin-activated myosin light chain kinase from Streptomyces sp.—I. isolation, structural determination and biological properties of MS-271

A novel cyclic peptide, MS-271, was isolated from the culture broth of an actinomycete, Streptomyces sp. M-271 as an inhibitor of smooth muscle myosin light chain kinase (MLCK). MS-271 inhibited the MLCK from chicken gizzard with an IC50 value of 8 microM. MS-271 did not inhibit cyclic AMP-dependent protein kinase, protein kinase C or calcium/calmodulin-dependent cyclic nucleotide phosphodiesterase at concentrations up to 400 microM. The primary structure of MS-271 was identical to that of siamycin I, an anti-HIV peptide isolated from a microbial source.

Bacitracin Production by Whole Cells Immobilized in Polyacrylamide Gel

Whole cells of Bacillus sp., bacitracin-producing bacteria, were immobilized in polyacrylamide gel prepared by using 5% total acrylamide (95% acrylamide monomer and 5% N, N′-methylenebis acrylamide). Bacitracin production by the immobilized whole cells was examined by using various fermentation media. In starch-bouillon medium, the initial activity of immobilized whole cells for bacitracin production was 20 to 25% that of an equivalent amount of washed cells. With successive utilizations in 1% peptone as reaction medium, activity of the immobilized whole cells increased gradually and reached a steady-state maximum having a value of 80 to 90% of the activity obtained initially with washed cells, whereas the washed cells lost most activity when utilized successively. What appeared to be growth of the bacteria in the gel was observed by electron microscopy. Therefore, the activation of immobilized whole cells during successive utilizations apparently resulted from the growth of whole cells in the gel, especially at the gel surface. Images

EI-1511-3, -5 and EI-1625-2, Novel Interleukin-1β Converting Enzyme Inhibitors Produced by Streptomyces sp. E-1511 and E-1625

EI-1511-3, -5 and EI-1625-2, novel interleukin-1 beta converting enzyme (ICE) inhibitors, were isolated from the culture broths of Streptomyces sp. E-1511 and E-1625. EI-1511-3, -5 and EI-1625-2 selectively inhibited the recombinant human ICE activity with IC50 values of 0.09, 0.38 and 0.2 microM, respectively. Taxonomy, fermentation of the producing strain and isolation of EI-1511-3, -5 and EI-1625-2 are described.