几种酶活抑制剂对红曲霉色素合成的影响

Effects of enzyme inhibitors on the pigment synthesis in Monascus anka

摘要:

红曲色素是天然安全的色素和防腐剂,根据代谢数据库选择了6种代谢途径关键酶的抑制剂,在基本培养基中考察这些抑制剂对红曲霉生长和合成色素的影响。甲羟戊酸合成途径的抑制剂邻氨基苯甲酸和3,4-二羟苯甲酸对红曲霉生长和色素生物合成都没有影响;莽草酸途径关键酶氨基苯甲酸合成酶的抑制剂三甲胺不抑制红曲霉的生长和色素的合成。在不影响红曲霉生长的浓度范围内,聚酮途径中β-酮酯酰-ACP合成酶的专性抑制剂碘乙酰胺(0.5mmol/L)抑制红曲色素合成程度达64.7%,非专性抑制剂咪唑(1mmol/L)抑制幅度达60%,聚酮途径硫酯酶的抑制剂2,4-二硝基氟苯(0.5mmol/L)强烈抑制红曲霉合成色素的活性,抑制程度达91.5%。相关酶活抑制的试验数据显示红曲霉可能经过聚酮途径合成红曲色素。

Abstract:

Monascus pigment is a natural, safe pigment and preservative. Six inhibitors of key enzymes from three metabolic pathways were chosen according to databases, and were used in basic medium to study their effects on the pigment synthesis in Monascus anka strain M5034. Trimethylamine, inhibitor of shikimic acid pathways, and anthranilic acid and 3,4-dihydroxybenzoic acid, inhibitors of mevalonic acid pathways, had no effects on the pigment biosynthesis. Pigment biosynthesis was severely inhibited by three inhibitors of the key enzymes in the polyketide pathways at the concentrations with no effects for growth of the strain. Iodiacetamide (lower than 0.5mmol/L), specific inhibitor of β-ketoacyl-acylcarrier protein (ACP) synthase, reduced remarkably the pigment synthesis by 64.7%; 1.0 mmol/L imidazole, being nonspecific inhibitor of ACP synthase, could strongly suppress the synthesis of pigment by 60%, and 0.5mmol/L 2,4-dinitrofluorobenzene, inhibiting the activity of thioesterase, strongly limited the pigment production with inhibitory extent up to 91.5%. All data implied that Monascus pigments might be synthesized through polyketide pathway.