LYSINE METABOLISM

2.  Lysine is an essential amino acid.
 It is a basic amino acid.
 Lysine is predominantly ketogenic amino
acid.
 Cereal proteins are deficient in lysine.
 lt does not participate in transamination
reactions.

3.  Some of the lysine residues in protein
structure are present as hydroxylysine,
methyllysine or acetyllysine.
 These derivatives can be hydrolysed to
liberate free lysine.

4.  Some of the lysine residues in proteins are
found in methylated form.
 The methyl groups are obtained from SAM.
 These proteins on degradation (by
proteolysis) will release the methyllysines.

5.  The trimethyllysine serves as a precursor for
the synthesis of carnitine.
 Carnitine is involved in the transport of fatty
acids to mitochondria for oxidation.
 Synthesis of carnitine from trimethyllysine is
a 4-step reaction involving oxidation, splitting
off glycine residue, dehydrogenation &
finally, oxidation.

6.  Lysine & hydroxy lysine residues of collagen
& elastin are important in cross linking.
 The epsilon amino group of lysine can form
Schiff bases, thus linking to proteins, e.g.
Pyridoxal phosphate with transaminases.
 Lysine is found large quantities in histones -
basic protein associated with nucleic acids.

7.  Textbook of Biochemistry – U Satyanarayana
 Textbook of Biochemistry – DM Vasudevan