Department of Biochemistry, Dr Babasaheb Ambedkar Marathwada University, Aurangabad 431004, Maharashtra, India.
J Sci Food Agric. 2011 Aug 15;91(10):1773-80. doi: 10.1002/jsfa.4380. Epub 2011 Mar 28.
Starchy seeds are an important food and a source of dietary ingredients in many countries. However, they suffer from extensive predation by bruchids (weevils) and other pests. α-Amylase inhibitors are attractive candidates for the control of seed weevils, as these insects are highly dependent on starch as an energy source.
A proteinaceous α-amylase inhibitor from the seeds of Achyranthes aspera was identified, purified and characterised. In electrophoretic analysis, two prominent amylase inhibitor activity bands (AI1 and AI2) were detected. The inhibitor was purified 9.99-fold with 1206.95 total amylase inhibitor units mg⁻¹ protein. The molecular weight of the purified inhibitor was around 6 kDa. The isolated α-amylase inhibitor was found to be resistant to heat and proteolysis. Feeding analysis of Callosobruchus maculatus larvae on a diet containing seed powder of A. aspera revealed that survival of the larvae was severely affected, with the highest mortality rate occurring on the fifth day of feeding. The isolated inhibitor inhibited the majority of amylase isoforms of C. maculatus, Tribolium confusum and Helicoverpa armigera in electrophoretic analysis and solution assays.
The information obtained in the present investigation could be useful for a genetic engineering approach that would make seeds resistant to storage pest infestations.
含淀粉的种子是许多国家重要的食物和膳食成分来源。然而，它们极易受到象鼻虫（豆象）和其他害虫的侵害。α-淀粉酶抑制剂是防治种子象鼻虫的理想候选物，因为这些昆虫高度依赖淀粉作为能量来源。
从牛膝的种子中鉴定、纯化并表征了一种蛋白性α-淀粉酶抑制剂。在电泳分析中，检测到两个明显的淀粉酶抑制剂活性带（AI1 和 AI2）。抑制剂经纯化后，比活提高了 9.99 倍，总淀粉酶抑制剂单位为每毫克蛋白质 1206.95 单位。纯化抑制剂的分子量约为 6 kDa。发现分离出的α-淀粉酶抑制剂耐热和抗蛋白水解。在含有牛膝种子粉的饲料上对绿豆象幼虫进行饲养分析表明，幼虫的存活率受到严重影响，在第五天的摄食中死亡率最高。分离出的抑制剂在电泳分析和溶液测定中抑制了绿豆象、赤拟谷盗和棉铃虫的大多数淀粉酶同工酶。
本研究获得的信息可能有助于采用基因工程方法使种子具有抗贮藏害虫侵害的能力。
