Text books:
Horton, H. Robert, Moran, Laurence, Ochs, Raymond, Rawn, David, Scrimgeour, K. Gray. 2002. Principles of Biochemistry. Upper Saddle River, NJ: Prentice Hall.
Nelson, David, Cox, Michael. 2000. Lehninger's Biochemistry. New York, NY: Worth.
Zubay, Geoffrey. 1998. Biochemistry. Dubuque, IA: W.C. Brown.
WWW links:
A chapter on Enzymes: http://ull.chemistry.uakron.edu/genobc/Chapter_20/
Biochemistry of neurotransmittors: http://web.indstate.edu/thcme/mwking/nerves.html
Peptide hormones: http://web.indstate.edu/thcme/mwking/peptide-hormones.html
Genetic defects in metabolic enzymes: http://web.indstate.edu/thcme/mwking/inborn.html
Oncogenes and cancer: http://web.indstate.edu/thcme/mwking/oncogene.html
Molecular models for Biochemistry (visualizing molecules on a PC): http://info.bio.cmu.edu/Courses/BiochemMols/BCMolecules.html
Biochemistry at the University of Kansas Medical School: http://www.kumc.edu/research/medicine/biochemistry/bioc800/start.html