The chromatographic fractionation of ribonuclease

Abstract

Vol. 49 GLUCURONIDE DECOMPOSITION IN THE RUMEN 215 2. The optimum pH for the decomposition of phenolphthalein glucuronide by the enzyme was 6*1.3. Irreversible inactivation of the enzyme occurred on incubation for a short period at a pH lower than 6 or higher than 7.4. On the assumption that the rate of liberation of phenolphthalein from the glucuronide was governed by a single reaction a value of 3 05 x 10m was obtained for the dissociation constant of the active enzyme-substrate complex. Excess substrate caused pronounced inhibition of the enzyme. The inactive complex contained two substrate molecules per active enzyme centre, and the second dissociation constant was 00126M. 5. Saccharate caused only slight inhibition of the enzyme in comparison with its effect on animal ,-glucuronidase.The authors wish to express their gratitude to Dr A. E Oxford for assistance and advice in microbiological aspects of this work, and to Dr A. T. Phillipson for the supply of sheep with rumen fistulae.

The crystal structure of ribonuclease. Comparison of three-dimensional Patterson vector maps of crystals grown from ethyl and tertiary butyl alcohol respectively

“…One striking feature of these crystals and of those subsequently grown in our laboratory both by Mr H. Dix and Mr M. Rosemeyer is the reproducibility of the X-ray patterns. This suggests that the differences which exist between the two chemically different types of ribonuclease A and B (Martin & Porter, 1951) must be very slight and is supported by the recent findings (Tanford & Hauenstein, 1956) that this difference is due solely to the presence of an additional earboxyl group in form B. As ribonuclease /3 contributes some 10 to 15% of the mixture we are clearly dealing with crystals which, for practical…”

Selection Against Glycosylation in Ruminant Pancreatic Ribonucleases by Replacements in the Ancestral Carbohydrate Attachment Site

“…One of the first successful applications of column chromatography in protein research was the separation of bovine pancreatic ribonucleases (RNase) A and B (Martin and Porter 1951 ; Hirs et al. 1953 ).…”

Consequences of the Endogenous N-Glycosylation of Human Ribonuclease 1

“…The “A” in RNase A refers not to an adenine nucleobase, but to RNase A being the predominant ribonuclease in the cow pancreas. , RNase A is unglycosylated, whereas RNase B, RNase C, and RNase D are N -glycosylated forms of RNase A. , The glycan is added to the side chain of Asn34 residue by oligosaccharyltransferase, which acts on Asn-Xaa-Ser/Thr sequons, − where Xaa represents any residue other than proline . RNase A has only one sequon.…”