STUDIES ON THE BIOCHEMISTRY OF EPIDERMIS .2. SOME CHARACTERISTICS OF DEOXYRIBONUCLEASE-I AND DEOXYRIBONUCLEAS-II OF ALBINO GUINEA PIG EPIDERMIS AND SALINE EXTRACTS OF HAIR

[摘要] In contrast to rat epidermis, which contains a high level of DNase II and no DNase I activity, guinea pig epidermis has both high DNase I and DNase II activities. The ratio is about 1.14. Saline extracts of guinea pig hair or washings from the skin surface contain high DNase I activity but only traces of DNase n. About 50% of guinea pig DNases I and II and rat DNase II can be removed by washing excised epidermis. This enzymatic activity is in the interstitial compartment or originates from the stratum corneum, or from both. The DNase II content of guinea pig epidermis is higher than that of any of the visceral organs tested; its DNase I level is exceeded only by that of the pancreas. Due to secondary changes caused by a skin surface dose of 3,000 rep beta irradiation, there is a progressive increase in epidermal extracellular DNase I, while DNase II remains unchanged or decreases by the tenth day. Evidence is presented that extracellular DNase I and DNase II activities originate primarily in the epidermis and not in the sebaceous glands or the blood. The possible role of nucleases in the disappearance of nucleic acids during keratinization is discussed.