The fourth edition of Lehninger Principles of Biochemistry stays true to the vision of its predecessors while embracing the advances made in biochemical research since the previous edition. As always, the book presents the fundamentals of biochemistry through selected topics, and emphasizes the most important recent developments and applications without abandoning the classical core of the subject. The new edition has been carefully streamlined to reduce the length of the book without compromizing content. As with previous editions, it emphasizes clear prose and student friendly explanations to optimize student comprehension. It also contains a groundbreaking new treatment of metabolic regulation, up to date coverage of DNA based information technologies, many new applications and problems, and a new graphical style for enzyme reaction mechanisms, including step by step annotations that clarify the concepts and chemical logic of enzymatic reactions. Lecturer supplements include: Instructor's Resource CD ROM with Test Bank, Printed Test Bank and a set of 150 Overhead Transparencies. For students a Study Guide and Solutions Manual is available which includes discussion questions, a self test and a Cellular Metabolic Map, as well as a Lecture Notebook containing the essential diagrams and reaction equations in the text. The textbook's dedicated website http://www whfreeman.com/lehninger offers numerous features including PowerPoint images, animated mechanisms and living graphs.