Purification and Some Enzymatic Properties of Acid Protease A and B of Scytalidium lignicolum ATCC 24568

Three kinds of acid proteases were purified from the culture filtrate of Scytalidium lignicolum ATCC 24568. About 3 mg of A–1, 6 mg of A–2 and 60 mg of B were obtained from one liter of culture broth. These purified enzymes were monodisperse by physicochemical criteria such as ultracentrifugal analysis and disc electrophoresis.

A–1 and A–2 were very similar to each other on their enzymatic properties except the small difference of isoelectric point. A–1 and A–2 were active between pH 3.0~3.5 toward casein, and stable between pH 2.5 and 5.5 for 20 hr at 37°C. Both enzymes were strongly inhibited by NBS, but not by EDTA, DFP and sulfhydryl reagents.

B was most active at pH 2.0, and stable at pH values between 1.5 and 5.0. This enzyme was also inhibited by NBS and KMnO₄, but not by EDTA, DFP and sulfhydryl reagents.

The molecular weights and isoelectric points of A–1, A–2 and B were 43,000, pH 3.6; 43,000, pH 3.8 and 22,000, pH 3.2, respectively.

A–1 and A–2 were not inhibited by S–PI and synthetic pepsin inhibitor such as diazoacetyl-dl-norleucine methylester (DAN) and 1,2-epoxy-3-(p-nitrophenoxy)-propane (EPNP). B was inhibited by EPNP, but not by S–PI and DAN.     

Isolation and Identification of ATP: Nucleotide Pyrophospho-transferase-producing Microorganism

ATP: nucleotide pyrophosphotransferase-producing microorganism was isolated from soil in Osaka prefecture. The morphological and physiological characteristics of this microorganism were studied. This strain was identified and named Streptomyces adephospholyticus nov. sp.

When this strain was aerobically cultured in a fermentor at 30°C in a medium containing 2% glycerol, 4% polypepton, 0.1 % KH₂PO₄, 0.04% MgSO₄ · 7H₂O, 2 ppm FeSO₄ · 7H₂O and 2 ppm MnSO₄ · 6Н₂О at pH 7.0, ATP; nucleotide pyrophosphotransferase was produced in the culture filtrate. The highest activity was obtained after 30 to 40 hr cultivation. The maximum enzyme production was 3000 to 4000 unit per liter.     

Synthesis of phosphorothioate oligonucleotide-peptide conjugates by solid phase fragment condensation

Phosphorothioate oligonucleotide-peptide conjugates were synthesized by solid phase fragment condensation (SPFC). Arginine rich peptides could be successfully conjugated in 2.8-13.4% isolated yields. All the products were fully characterized by reversed phase HPLC and MALDI-TOF-MS to give satisfactory results.     

Cell filamentation in an Escherichia coli K-12 fic mutant caused by theophylline or an adenylate cyclase gene (cya)-containing plasmid

Abstract The bioconversion of 17α-ethynyl steroids was effected with 11α-hydroxylase of Rhizopus nigricans . 7β-Hydroxyethisterone was found after the bioconversion of ethisterone, and 10β- and 6β-hydroxy derivatives after the bioconversion of norethisterone. It seems that the ethynyl group prevents steroid-enzyme binding in the normal mode and thus inhibits the formation of an 11α-hydroxylated product.     

Comparative studies of suidatrestin, a specific inhibitor of trehalases

Suidatrestin, isolated from a Streptomyces strain, was characterized as a new trehalase inhibitor. Its inhibitory potential was 7 to 50-fold higher than that of validamycin when tested against insect, fungal and mammalian trehalases. The kinetic properties of suidatrestin were studied in vitro with trehalases from flight muscle mitochondria of the fly, Protophormia terraenovae, from larval midgut of the moth, Spodoptera littoralis, and from porcine kidney, as well as with maltase from yeast. Suidatrestin was inactive on maltase but inhibited all trehalases with IC₅₀ values of 0.08–0.1 μM; K_i values ranged from 0.02 to 0.05 μM. The very low K_i/K_m ratios (3.9×10⁻⁶–4.9×10⁻⁶) indicated excellent in vitro inhibitory action of suidatrestin. When injected into larvae of S. littoralis, suidatrestin required high and repetitive doses which lead to reversible inhibition of larval growth only. Consecutive omission of the inhibitor even stimulated weight increase above that of controls. Significant mortality was achieved at a rather high dose only. Injection of a growth-inhibiting dose of suidatrestin did not change hemolymph osmolality as a measure of sugar concentration. The discrepancy between in vitro and in vivo potency of suidatrestin may be understood once its chemical structure is fully known.     

Complete amino acid sequence of Scytalidium lignicolum acid protease B

The acid protease B (SLB) of Scytalidium lignicolum was reduced and carboxymethylated and then subjected to tryptic digestion. Five fragments were isolated and some of them were further digested with alpha-chymotrypsin, thermolysin, and dilute acetic acid. The sequence analysis of these fragments and the peptides by conventional methods established the complete amino acid sequence of SLB. The enzyme was composed of 204 amino acid residues with threonine and valine as its amino- and carboxyl-termini, respectively. Locations of three disulfide bridges were also established to be Cys47-126, Cys140-163, and Cys192-201 by enzymatic fragmentation of the denatured and unmodified SLB. Only a slight homology was found in the sequences of SLB and other acid proteases hitherto reported.     

Histochemical localization of kallikrein-like pro-phe-arg-naphthylester esterase activity in the rat kidney

Summary In the rat kidney the presence of the kallikrein-like pro-phe-arg-naphthylester esterase activity was demonstrated by a simultaneous coupling azo dye method. The enzyme was identified as a serine-protease because it was inhibited by preincubation with diisopropyl-fluorophosphate and unaffected by sodium iodoacetate. Since kallikrein is a serine-protease and pro-phe-arg-naphthylester is a synthetic and sensitive substrate for kallikrein, the enzyme activity revealed by this method was considered to represent kallikrein, although non-kallikrein esterase activity is not totally excluded. The enzyme activity was localized mainly in the outer stripe of the outer medulla, with focal extensions primarily only in the lower half of the cortex corresponding to the medullary rays.