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A Practical Introduction to Structure, Mechanism, and Data Analysis - Part 8

Các hoạt động của một enzyme có thể bị chặn trong một số cách khác nhau. Ví dụ, các phân tử ức chế có thể liên kết với các trang web trên các enzyme gây trở ngại cho doanh thu thích hợp. Chúng tôi gặp phải những khái niệm chất nền và ức chế sản phẩm | Enzymes A Practical Introduction to Structure Mechanism and Data Analysis. Robert A. Copeland Copyright 2000 by Wiley-VCH Inc. ISBNs 0-471-35929-7 Hardback 0--471 220 63-9 Electronic 8 REVERSIBLE INHIBITORS The activity of an enzyme can be blocked in a number of ways. For example inhibitory molecules can bind to sites on the enzyme that interfere with proper turnover. We encountered the concept of substrate and product inhibition in Chapters 5 6 and 7. For product inhibition the product molecule bears some structural resemblance to the substrate and can thus bind to the active site of the enzyme. Product binding blocks the binding of further substrate molecules. This form of inhibition in which substrate and inhibitor compete for a common enzyme species is known as competitive inhibition. Perhaps less intuitively obvious are processes known as noncompetitive and uncompetitive inhibition which define inhibitors that bind to distinct enzyme species and still block turnover. In this chapter we discuss these varied modes of inhibiting enzymes and examine kinetic methods for distinguishing among them. There are several motivations for studying enzyme inhibition. At the basic research level inhibitors can be useful tools for distinguishing among different potential mechanisms of enzyme turnover particularly in the case of multisubstrate enzymes see Chapter 11 . By studying the relative binding affinity of competitive inhibitors of varying structure one can glean information about the active site structure of an enzyme in the absence of a high resolution three-dimensional structure from x-ray crystallography or NMR spectroscopy. Inhibitors occur throughout nature and they provide important control mechanisms in biology. Associated with many of the proteolytic enzymes involved in tissue remodeling for example are protein-based inhibitors of catalytic action that are found in the same tissue sources as the enzymes themselves. By balancing the relative concentrations of the