When an amino acid is converted to a keto acid, the alpha amino group of the amino acid (-NH3) is converted to a keto group (-C=O).
protein is of course one of the last sources for fuel, but if ur body needs it, the protein will lose its amino group and will go through cellular respiration starting at glycolysis.the amino acid...
pyruvate
They are burned for energy.
reabsorbed completely unless their concentrations in the filtrate exceed their transport maximum