Enzyme specificity and catalysis

Published on April 19, 2020 Reviewed on November 27, 2022   43 min

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A selection of talks on Biochemistry

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Hello. Welcome to this Principles of Biochemistry lecture series. I am Jerry Feigenson. I am a professor in the Department of Molecular Biology and Genetics at Cornell University in the USA. In the seventh lecture, you saw that haemoglobin is an ideal oxygen carrier because it picks up oxygen in the lungs, then changes its structure to drop off oxygen in oxygen starved tissue. Haemoglobin quaternary structure has two different forms, a tensed form that is stabilized by many pH dependent ion pairs and a relaxed form that loses all these ion pairs. Many hundreds of proteins besides haemoglobin have these tense and relaxed quaternary structures, which is called the two-state model. We saw that fetal haemoglobin has higher oxygen affinity than maternal haemoglobin in part because of the loss of ion pairs.
In this eighth lecture, you will learn that there is an Enzyme Commission, and it needs only seven categories to describe every enzyme. Different enzymes have different degrees of binding specificity. We will look at the basic principles of enzyme kinetics. Then we will consider a very interesting question, why chemical reactions take time to occur? We will see that this depends on the Boltzmann distribution. Then we'll talk about a really fascinating subject, how enzyme catalysts work. In brief, they can bind the transition state and stabilize it, and they can force the reaction along a different pathway than the uncatalyzed reaction.