SPIRO, KARL (1867–1932), German physiological chemist. Born in Berlin, he worked at the University of Strasbourg from 1894 until 1918, when it became difficult there for Germans, and he went to Switzerland. From 1921 he was professor of physiological chemistry at the University of Basle. He was one of the first to apply concepts of physical chemistry to biology, such as pH buffering, and chemical kinetics to enzyme actions. He discovered some of the building blocks of proteins, such as pyrrolidinecarboxylic acid and phenylethylamine.