Intracellular predominant ribonuclease (EC 3.1.27.2) in the stationary phase cells of Bacillus cereus IF0 3131 was purified about 3,400-fold to a homogeneous state. The ribonuclease was identified to be of the nonspecific cyclizing type, devoid of cyclic phosphodiesterase activity, as the final reaction products proved to be nucleoside 2',3'-cyclic monophosphates. Molecular weight was estimated...

Ribonuclease A (RNase A; EC 3.1.27.5) was perhaps the most studied enzyme of the 20th century and is the best characterized ribonuclease. The “A” in its name refers not to its substrate specificity, but to the predominant form of the enzyme produced by the bovine pancreas. RNase A is unmodified, whereas RNase B, RNase C, and RNase D are mixtures of glycoforms. Because of its availability in lar...

The complex formed between the enzyme ribonuclease T1 (EC 3.1.27.3) and its specific inhibitor 2'-guanylic acid (2'-GMP) has been refined to R = 0.180 using x-ray diffraction data to 1.9-A resolution. The protein molecule displays a compact fold; a 4.5 turn alpha-helix packed over an antiparallel beta-pleated sheet shields most of the hydrophobic interior of the protein against the solvent. The...

Rana catesbeiana ribonuclease (RC-RNase) is a pyrimidine-guanine sequence-specific ribonuclease found in R. catesbeiana (bullfrog) oocytes. It possesses both ribonuclease activity and cytotoxicity against tumor cells. We report here for the first time the cloning of RC-RNase cDNA from liver rather than from oocytes where RC-RNase is stored. An internal fragment of cDNA was obtained by reverse t...

1. The activity of soluble ribonuclease and deoxyribonuclease first declined during senescence, but later increased during advanced stages of senescence. 2. Young leaves had very low ribonuclease or deoxyribonuclease activity associated with the chromatin, but the activity of these enzymes increased progressively during senescence until the leaves died. 3. No significant changes in the composit...

Aqueous solutions of polyhydric alcohols protect the native conformation of ribonuclease against denaturation by heat, acid, and urea. The protective effect increases with the length of the molecule of the polyhydric alcohol and with its concentration. This stabilizing effect is explained in terms of a lessened hydrogen bond-rupturing capacity of the medium. Aqueous solutions of monovalent alco...

Mounting evidence suggests that human pancreatic ribonuclease (RNase 1) plays important roles in vivo, ranging from regulating blood clotting and inflammation to directly counteracting tumorigenic cells. Understanding these putative roles has been pursued with continual comparisons of human RNase 1 to bovine RNase A, an enzyme that appears to function primarily in the ruminant gut. Our results ...

Ribonucleases with antitumor activity are mainly found in the oocytes and embryos of frogs, but the role of these ribonucleases in frog development is not clear. Moreover, most frog ribonuclease genes have not been cloned and characterized. In the present study, a group of ribonucleases were isolated from Rana catesbeiana (bullfrog). These ribonucleases in mature oocytes, namely RC-RNase, RC-RN...

A mutant of ribonuclease T1 (RNase T1), denoted RNase Talpha, that is designed to recognize double-stranded ribonucleic acid was created. RNase Talpha carries the structure of RNase T1 except for a part of its loop L3 domain, which has been swapped for a corresponding domain from alpha-sarcin. The RNase Talpha maintains the pleated beta-sheet structure and retains the guanyl-specific ribonuclea...

We have developed a simple and sensitive method for the rapid quantitation of mRNA from cell cultures and small tissue samples. The method combines the high sensitivity and specificity of the ribonuclease protection assay with simple handling and rapid execution of dot blotting. The use of digoxygenin-labeled cRNA probes eliminates all problems associated with radioisotopes commonly used in the...