New inhibitors of melanogenesis, OH-3984 K1 and K2. II. Physico-chemical properties and structural elucidation.
New melanin synthesis inhibitors, OH-3984 K1 and K2, were isolated from the fermentation broth of Streptomyces sp. OH-3984, and their structures were elucidated by spectroscopic methods and by chemical transformations. OH-3984 K1 (M.W.: 306; C18H26O4) and K2 (M.W.: 308; C18H28O4) have unique gamma-lactone rings, both of which correspond to oxidative products derived from C1-O14 cleavage of the 14-membered lactone group.
Biomodification of albocycline by Streptomyces venezuelae.
The macrolide antibiotic albocycline, when added to the fermentations of Streptomyces venezuelae UC-2560 (WC-3627) underwent a gradual loss of antimicrobial activity. The inactive product of this biotransformation was isolated from the fermentations and was shown to be 2,3-dihydroalbocycline.
Isolation and characterization of variant cDNAs encoding mouse tyrosinase.
Two different cDNA clones encoding mouse tyrosinase (monophenol oxygenase, E.C. 1.14.18.1) were isolated from B16 melanoma cells, and their primary structure was determined. One of the cDNAs consists of 3309 nucleotides with an open reading frame coding for a peptide of 533 amino acids. The other cDNA is approximately 1600 nucleotides long, with a shorter 3'-untranslated region and a deduced in-frame deletion of 77 amino acid residues with respect to the former clone. Neither of these clones is structurally identical to other described mouse tyrosinase cDNAs (1-3). RNA blotting analysis demonstrates that multiple tyrosinase mRNA species are not only present in B16 melanoma, but also in normal skin melanocytes.