Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tryptophan residues in ribonuclease from a Rhizopus sp. (RNase Rh) were modified by NBS, H2O2-dioxane, o-nitrophenylsulfenyl chloride (NPS-Cl) and the relation between the extent of modification and enzymatic activity was studied in each case. By extrapolation of the modified tryptophan residue-enzymatic activity curve to a completely inactive state, it was found that modification of 1-2 tryptophan residues is responsible for loss of enzymatic activity. RNase Rh was partly protected from modification by H2O2-dioxane (pH 8.4) and NPS-Cl (pH 3.5) when in the presence of 2'-AMP and the fluorescence emission spectrum of RNase Rh was quenched by adding 2'-AMP. It seems, therefore, that 1 or 2 tryptophan residues are involved in the active site of RNase Rh or are located near the active site. The solvent perturbation difference spectra of RNase Rh were measured using ethylene glycol and D2O as perturbants. The results indicated that 1.2 tryptophan residues for D2O and 1.9 tryptophan residues for ethylene glycol were exposed to the solvents. These data show that about 1.2-1.9 tryptophan residues are exposed to the solvent and their modification causes loss in enzymatic activity.
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PMID:Chemical modification of tryptophan residues in ribonuclease from a Rhizopus sp. 739 Sep 80

A new method for the bonding of diethylamine(DEA) on the surface of silica to prepare novel hydrophilic packings for HPLC has been studied. After allyl glycidyl ether being synthesized, the Si-DEA anion-exchange bonded phase was prepared by the reaction of the double bond in allyl group with Si-H silica. The bonded phases obtained were characterized by elemental analysis, diffuse reflectance infrared Fourier transform(DRIFT) spectroscopy and HPLC evaluation. The methods were used for both porous silica and monodisperse non-porous silica. The contents of carbon, hydrogen and nitrogen of porous Si-DEA packing (MPS-DEA) were 3.31%, 0.95% and 1.34% respectively and those of monodisperse non-porous Si-DEA packing (NPS-DEA) were 2.55%, 0.97% and 0.96% respectively. The diethylamine absorption peak can be observed at 2970 cm-1 from the Si-DEA silica DRIFT spectrum. These data revealed that the diethylamine had been bonded on MPS-DEA and NPS-DEA packings. In HPLC tests, nucleotides and nucleosides such as cytosine, uracil, cytidine-5'-monophosphate, adenosine-5'-monophosphate, inosine-5'-monophosphate and guanosine-5'-monophosphate were satisfactorily separated on the porous anion-exchange packing (MPS-DEA), and a group of proteins (lysozyme, ribonuclease, ovalbumin, bovine serum albumin, insulin and gamma-globulin) were separated within 15 minutes successfuly. All test results indicated that the new method for preparing better anion-exchange silica packings is effective for both porous silica and monodiperse non-porous silica.
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PMID:[Preparation and evaluation of new ion-exchange chromatographic stationary phase for the use in high performance liquid chromatography]. 1255 75