General Enzymatic Properties of Human Histidine Acid Phosphatase-Phytase

The glycosylated human MINPP (multiple inositol polyphosphate phosphatase), which was recombinantly over-expressed by using industrial host, Pichia pastoris, showed the phytase activity against phytate ($InsP_6$) and the enzyme activity of the unglycosylated counterpart was decreased to 30%. The optimal phytase activity occurred at pH 7.4. The human MINPP showed high substrate specificity for $InsP_6$ with little activity on other organic phosphate conjugates such as para-nitrophenylphosphate (pNPP), ATP, and ribose-1-phosphate (R-1-P). The phosphatase activity against 2,3-bisphosphoglycerate (2,3-BPG) by human MINPP was increased to 1.2-fold in the presence of stimulator, 1 mM 2-phosphoglycolate (2-PG) but the phytase activity against $InsP_6$ was not affected by addition of 1 mM 2-PG. The phosphatase activity against 2,3-BPG by human MINPP was not increased in the presence of 2 mM $Mg^{2+}$ or 100 mM $Cl^-$.

히스티딘 에시드 포스파테이즈(Histidine Acid Phosphatase) 계열 인간 파이테이즈(Phytase)의 일반적 특성규명

산업용 균주인 Pichia pastoris에서 재조합 발현된 당화된 인간유래 MINPP (multiple inositol polyphosphate phosphatase) 효소는 기질 피틴태인(InsP6)에 대한 파이테이즈 효소활성을 나타내었고 탈당화시 그 효소활성이 30% 감소되었다. 그 효소의 기질 $InsP_6$에 대한 최적 pH 활성은 중성범위인 pH 7.4였다. 기질특이성 측면에서 인간 MINPP 효소는 para-nitrophenylphosphate (pNPP), ATP, ribose-1-phosphate (R-1-P)와 같은 유기인산화합물(organic phosphate conjugates)의 분해활성은 매우 낮은 대신, 기질 $InsP_6$를 효과적으로 분해하였고 특히 화학적 자극제인(chemical stimulator)인 1 mM 2-phosphoglycolate (2-PG)의 첨가에 따른 기질 2,3-bisphosphoglycerate (2,3-BPG)에 대한 효소활성이 2-PG를 첨가하지 않을때 보다 1.2배 증가되었지만 기질 $InsP_6$에 대한 효소활성에는 영향을 주지 않았다. 또한 2 mM $Mg^{2+}$ 이온과 100 mM $Cl^-$ 이온의 첨가는 MINPP 효소의 기질 2,3-BPG에 대한 효소활성에 역시 영향을 주지 않았다.