Valine is a branched chain amino acid. An "ideal protein" would contain 70% as much isoleucine as lysine. Valine (click for Almanac at Excite info on threonine).

A rare, inherited metabolic disease in which there is a failure of oxidative decarboxylation (breakdown) of valine, leucine and isoleucine results in maple syrup urine disease, named because of a characteristic odor of the urine.

Another resource on Valine is smartbasics. However, it is a commercial source of information, so be careful. The information appears to be valid, and it has a glossary general index for amino acids.

Further information on other amino acids can be found at the Infoplease Almanac at EXCITE and at http://www.chemie.fu-berlin.de which is in Germany (choose the English versions).