Analysis on Enzymatic Browning in Pine Needles

Abstract

Tyrosinases are related to the enzymatic browning of plants and attract the major scientific interest for the prevention of it. Three tyrosinase isozymes (P1, P2 and P3) from pine needles were purified to homogeneity and characterized the factors that affect their activities. The L-ascorbic acid and β-mercaptoethanol notably inhibited the enzymatic activities of the three isozymes. The sodium diethyldithiocarbamate was a competitive inhibitor of isozymes with the Ki values of P1(0.030 mM), P2(0.015 mM) and P3(0.019 mM), respectively. Their enzyme activities were however, increased by the addition of most metal ions. The optimum pH for the three isozymes was 9.0~9.5 and the optimum temperatures ranged from 55 to 60℃ using L-DOPA as substrate.

Tyrosinase는 식물의 갈변현상에 관계가 있으며, 이의 방지를 위한 방법의 개발은 과학적인 관심사가 되고 있다. 솔잎으로부터 3개의 tyrosinase isozyme을 정제하여 그들의 활성에 영향을 주는 인자들을 분석하였다. L-ascorbic acid와 β-mercaptoethanol은 효소의 활성을 크게 저해하였다. 또한 sodium diethyldithio-carbamate도 효소활성에 대한 경쟁적 저해제였으며, Ki 값은 P1(0.030 mM), P2(0.015 mM), P3(0.019 mM)이였다. 반면 대부분의 금속이온들은 효소활성을 증가시켰다. L-DOPA를 기질로 사용했을 때 효소의 최적 pH는 9.0~9.5이며, 최적 온도는 55∼60℃를 나타내었다.