Abstract
A crystalline enzyme capable of digesting thymus nucleic acid (desoxyribonucleic acid) has been isolated from fresh beef pancreas. The enzyme called "desoxyribonuclease" is a protein of the albumin type. Its molecular weight is about 60,000 and its isoelectric point is near pH 5.0. It contains about 8 per cent tyrosine and 2 per cent tryptophane. It is readily denatured by heat. The denaturation is reversible if heated in dilute acid at pH about 3.0. The digestion of thymus nucleic acid by crystalline desoxyribonuclease is accompanied by a gradual increase in the specific absorption of ultraviolet light by the acid. The spectrophotometric measurement of the rate of increase in the light absorption can be conveniently used as a general method for estimating desoxyribonuclease activity. Details are given of the method for isolation of crystalline desoxyribonuclease and of the spectrophotometric procedure for the measurement of desoxyribonuclease activity.
Full Text
The Full Text of this article is available as a PDF (865.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Goodwin T. W., Morton R. A. The spectrophotometric determination of tyrosine and tryptophan in proteins. Biochem J. 1946;40(5-6):628–632. doi: 10.1042/bj0400628. [DOI] [PMC free article] [PubMed] [Google Scholar]
- King E. J. The colorimetric determination of phosphorus. Biochem J. 1932;26(2):292–297. doi: 10.1042/bj0260292. [DOI] [PMC free article] [PubMed] [Google Scholar]