Ji C, Norton R A, Wicklow D T, Dowd P F
National Center for Agricultural Utilization Research, Bioactive Agents Research, Agricultural Research Service, U.S. Department of Agriculture, Peoria, Illinois 61604, USA.
J Agric Food Chem. 2000 Feb;48(2):507-11. doi: 10.1021/jf9905119.
Isoform patterns of chitinase and beta-1,3-glucanase of maturing kernels of yellow dent corn (Pioneer 3394) infected with Aspergillus flavus at the milk stage were investigated through polyacrylamide gel electrophoresis (PAGE). Proteins on the sodium dodecyl sulfate (SDS) gel with an apparent molecular mass range of 23-46 kDa were differentially present in the kernels infected with both aflatoxin-producing and non-aflatoxin-producing strains of A. flavus. From in-gel (native PAGE) enzyme activity assays, three bands corresponding to chitinase isoforms and two bands corresponding to beta-1,3-glucanase isoforms were detected in the infected kernels. One chitinase isoform of 29 kDa was present only in the infected kernels, and another one of 28 kDa was present in both infected and noninfected kernels. They were judged to be acidic on the basis of their migration on an acrylamide isoelectric focusing (IEF) gel. For the beta-1,3-glucanase, one isoform of 35 kDa was present in both infected and noninfected kernels, but another one, a 33 kDa isoform, was present only in the infected kernels. Both acidic and basic beta-1,3-glucanase isoforms were detected in the IEF gel. The results of this study are the first to demonstrate patterns of enhanced or inducible proteins in maturing corn kernels in response to A. flavus infection at the milk stage. The results also indicate that only particular isoforms of the two hydrolytic enzymes are involved in the maturing corn kernels infected at the milk stage with A. flavus.
通过聚丙烯酰胺凝胶电泳（PAGE）研究了处于乳熟期感染黄曲霉的黄色马齿型玉米（先锋3394）成熟籽粒中几丁质酶和β-1,3-葡聚糖酶的同工型模式。在感染了产黄曲霉毒素和不产黄曲霉毒素菌株的籽粒中，十二烷基硫酸钠（SDS）凝胶上表观分子量范围为23 - 46 kDa的蛋白质存在差异。通过凝胶内（天然PAGE）酶活性测定，在受感染的籽粒中检测到三条对应于几丁质酶同工型的条带和两条对应于β-1,3-葡聚糖酶同工型的条带。一种29 kDa的几丁质酶同工型仅存在于受感染的籽粒中，另一种28 kDa的几丁质酶同工型在受感染和未受感染的籽粒中均存在。根据它们在丙烯酰胺等电聚焦（IEF）凝胶上的迁移情况判断它们为酸性。对于β-1,3-葡聚糖酶，一种35 kDa的同工型在受感染和未受感染的籽粒中均存在，但另一种33 kDa的同工型仅存在于受感染的籽粒中。在IEF凝胶中检测到了酸性和碱性的β-1,3-葡聚糖酶同工型。本研究结果首次证明了乳熟期玉米籽粒中响应黄曲霉感染而增强或可诱导的蛋白质模式。结果还表明，只有这两种水解酶的特定同工型参与了乳熟期感染黄曲霉的成熟玉米籽粒。
