Non-Protein Amino Acids
Non-protein amino acids
about 700 amino acids are known, at least 300 from plants
three major routes for origin
a) modification of existing (often protein) amino acid
b) modification of an existing pathway
c) novel pathways
Found mostly in a small number of families
Fabaceae or Leguminosae
seeds of Cucurbitaceae
Sapindaceae, Aceraceae, Hippocastanaceae
microbes
Hypoglycine A and B
potent hypoglycemic factors from akee, Blighia sapida
mimosine
found in Mimosa species, but also in Leucaena leucocephala
interferes with tyrosine metabolism
Canavanine
found in 1500 species and 240 genera of Fabaceae: Papilionoideae examined
Dioclea seeds, 13% dry weight canavanine
insect uses for N-source
arginase activity ----> arginine ----> ornithine
canavanine ----> canaline + urea
insect has 30 times more urease than most other insects
Azetidine-2-carboxylic acid
often toxic because it replaces proline
Lathyrus and Vicia species
lathyrism
neurotoxins
3,4-Dihydroxyphenylalanine
DOPA ... related to dopamine
relationship to Parkinson's Disease
5-Hydroxytryptophan
similar to serotonin
5-hydroxytryptophan can cross blood brain barrier whereas serotonin cannot
6-10% hydroxytryptophan in Griffonia simplicifolia
Selenium-containing amino acids
selenium often replaces S in amino acids
may be facultative or obligate
almost always associated with high selenium in soils
Sulfur-containing amino acids in onion and garlic
alliin S-allylcysteine sulfoxide
breaks down to lachrymators
ammonia, sulfuric acid, hydrogen sulfide and low molecular weight carbonyl compounds
anticancer effects
Iron uptake and transport
(+)-nicotianamine
some grasses make siderophores that have similar structures. These compounds scavenge iron and limit
growth of other plants
Ethylene
a plant hormone or plant growth factor that is found in all plants. Involved in maturation of fruits.
comes from 1-aminocyclopropane 1-carboxylic acid HCN produced as a by product.
4-Methyleneglutamic acid synthesis
Isoleucine-derived amino acids
Miscellaneous non-protein amino acids
Non-protein amino acids from Lathyrus
Selenium-containing amino acids
Plants with non-protein amino acids
© David S. Seigler, Integrative Biology 425, Plant Secondary Metabolism, Department of Plant
Biology, 265 Morrill Hall, 505 S. Goodwin Ave., University of Illinois, Urbana, Illinois 61801, USA.
217-333-7577. seigler@life.uiuc.edu.
