以蕹菜種子萌芽期間光照與植物生長調節素對水解酵素活性的影響情形為
探討重點。蕹菜種子兼具明顯胚乳及子葉，且萌芽期間，光照下生長的幼
苗，其分叉形的子葉會呈綠色可行光合作用。乾種子的胚乳細胞呈不規則
薄片狀；浸水後胚乳細胞即吸水漲大，此時細胞形狀及大小相差甚大，且
細胞內充滿了澱粉顆粒；此外，由於染色後，未見胚乳細胞的細胞核，因
此推測蕹菜的胚乳細胞為死細胞。蕹菜種子胚乳中的α-及β-澱粉水解酵
素不受gibberellin、6-benzylaminopurine ( BAP )及光照有無的影響。
一般而言，6-benzylaminopurine對蕹菜種子子葉中的水解酵素較
gibberellin有促進作用；此外，光照下的水解酵素活性亦較高。 利用
cycloheximide的處理，顯示萌發幼苗子葉中的α-amylase、β-amylase、
protease及acid phosphatase的活性隨著萌發時間而增高，為酵素分子de
novo synthesis所致。而胚乳中的α-amylase及β-amylase在乾種蕹菜種
子在萌芽期間出現了四個主要的澱粉水解酵素，其中有二個為β-amylase
。利用isoelectric focusing (IEF) 及膠體過濾層析(gel filtration)
純化Rf值為0.394的β- amylase，純化率為26倍；以β-limit dextrin為
( monomer )。以馬鈴薯澱粉( potato starch )為受質，反應的最適溫度
為50℃。反應的最適pH值為5.5。對熱的耐受性，將酵素液在70℃處理，
5分鐘之內即完全失去活性。此外，其活性受到Fe+3、Cu+2、Hg+2、Sn+2
的抑制。

The effects of light and various growth regulators on the
hydrolase activities in the cotyledon and endosperm of
germinating water spinach were investigated. For endosperm, the
treatments of gibberellin, 6-benzyl-aminopurine, and light
irradiation do not influenced the activities of both α- and
β-amylases. For cotyledon, the treatment of BAP is more
effective than GA in inducing the activities of protease and
acid phosphatase. During germination, very high activities of
both α- and β-amylases were detected in the endosperms. but
they decay very rapidly in the first 1.5 days. This decay can be
slowed down by cycloheximide treatment, indicating that at least
one newly synthesized protein is required for this decay.
The treatment of cycloheximide also suppresses the otherwise
increase of hydrolase activities in the cotyledon. This result
demonstrates that the increase of enzymatic activities is due to
a de novo synthesis of protein. Four amylolytic isozymes,Amy-Ⅰ,
Ⅱ,Ⅲ,Ⅳ were separated and observed on native gel by activity
staining after electrophoresis. Amy-Ⅰ,Ⅱ might be α-amylases,
while Amy-Ⅲ,Ⅳ might be β-amylases. Water spinach β-amylase
(Amy-Ⅲ) was purified from endosperm by isoelectric focusing
(IEF) and gel filtration chromatography. The purified Amy-Ⅲ was
identified to be a β-amylase by β-limit dextrin as substrate.
The molecular weight of water spinach β-amylase (Amy-Ⅲ) was
determined to be 63kd or 69kd monomers by SDS-PAGE. The optimal
pH for catalysis was 5.5; the opitimal temperature for catalysis
was 50℃. β-amylase was rapidly inactived at by heating at 70℃
. The enzyme was inhibited by heavy metals that indicated
cysteinyl sulfhydryls are directly involved in catalytic site(s).
The effects of light and various growth regulators on the