John W. Rothrock

Polynucleotide phosphorylase covalently bound to cellulose and its use in the preparation of homopolynucleotides

Abstract A readily prepared, crude concentrate of polynucleotide phosphorylase (PNPase) has been covalently bound by the method of Porath to cyanogen bromide-activated cellulose; this is the first report of a synthesizing enzyme bound to a solid support. The bound enzyme had good activity and stability; more than forty consecutive polymerization cycles of nucleoside diphosphates have been carried out with a single preparation to give consistently good yields of stable polymers, and these were readily separated from the bound phosphorylase without tedious phenol extractions.

Inhibition of procine kidney “enkephalinase” by substituted-N-carboxymethyl dipeptides

Abstract A design effective for generating inhibitors of angiotensin converting enzyme has been successfully extended to inhibitors of another Zn ++ peptidase. A series of potent inhibitors for the zinc metalloendopeptidase associated with porcine kidney microsomes has been developed. Most contain the (S)-N-(1-carboxy-3-phenylpropyl)-L-Phe-X backbone. The most effective inhibitors with ID 50 values in the 10 −7 M range at pH 7.5 and 22°C were those where X = glycine, β-alanine, γ-amino butyric acid. A simple nomenclature designating substituted N-carboxy-methyl amino acid derivatives as -[N]- sharing amino acid derivatives is described.

Isolation of diosgenin by microbiological hydrolysis of saponin.

Abstract By microbial hydrolysis the saponins in pulverized Dioscorea tuber have been cleaved into the component parts, diosgenin and the sugar moieties. In one case a derivative, Δ 4 -diosgenone, was isolated. Although a wide range of conditions may be used in this conversion, the simplest include a mixed culture fermentation of pulverized fresh or dry tuber slurry aerated by stirring for 3–6 days at room temperature and maintained near pH 4. The yields are comparable to those obtained by acid hydrolysis. Only fungi were found to effect this conversion.

Guanosine-5′-monophosphate dioxanate: Preparation, characterization, and application

Abstract This paper reports, for the first time, the preparation and characterization of a unique crystalline complex of guanosine-5′-monophosphate, dioxane, and water (GMP-dioxanate) in a 1:1:1 molar ratio. The specificity of this complex is shown by the fact that no other solvent has been found which can replace dioxane. In addition, no other nucleotide or solvent combination has been found which forms a crystalline complex. GMP-Dioxanate is stable to heating and drying and is readily converted to the disodium salt. The compound has been fully characterized by physical, chemical, and biological analyses. Its crystallinity has been confirmed by both microscopic and X-ray analyses. Data on the optical rotation of solutions of GMP-dioxanate as a function of wavelength, concentration, and pH are described and compared with those of GMP and GMP·2Na·2H 2 O. This complex has provided a simplified procedure for the isolation of GMP from acid and salt mixtures, fermentation broths, and ribonucleic acid hydrolyzates.