Many enzymes will not work without the presence of an additional nonprotein substance called a cofactor. 许多酶如不外加一种叫做辅助因子的非蛋白质物质就不能工作。
As the main protein in red blood cells of human, hemoglobin is the basic substance that transports oxygen in blood. 摘要血红蛋白为人体红细胞中的一种主要蛋白质，是血液中运输氧气的主要物质。
