Aromatic Biosynthesis and Secondary Metabolism Flashcards

Vocabulary flashcards reviewing plant pathways, intermediates, and key concepts in aromatic, amino acid, and isoprenoid biosynthesis.

Shikimic Acid Pathway

The primary carbohydrate-derived pathway for the biosynthesis of phenylpropane derivatives, such as phenylalanine and tyrosine, named after its key intermediate shikimic acid.

Chorismic Acid

A major branching point intermediate in the shikimic acid pathway that serves as the substrate for anthranilate synthase and chorismate mutase.

Anthranilate Synthase

An enzyme that utilizes chorismic acid to produce anthranilic acid (a precursor of tryptophan) and is controlled by tryptophan acting as a feedback inhibitor.

Chorismate Mutase

An enzyme that converts chorismic acid into prephenate, the precursor of phenylalanine and tyrosine.

Acetate Hypothesis

A proposed route for aromatic compound synthesis involving the condensation of malonyl units with a terminal acetyl unit or malonamide-SCoA starter unit.

Compounds of Mixed Biogenetic Origin

Aromatic derivatives formed by the combination of the shikimic acid pathway and the acetate pathway, including stilbenes, isoflavones, flavones, and rotenoids.

Reductive Amination

The process through which nitrogen enters metabolism by converting $\text{a}$-keto acids (pyruvic, oxalacetic, and $\text{a}$-ketoglutaric acid) into alanine, aspartic acid, and glutamic acid.

Glutamic Acid Dehydrogenase

An enzyme functioning in conjunction with NAD in plant tissues that plays a central role in amino acid metabolism.

Biogenetic Isoprene Rule

A concept proposed by Ruzicka in 1953 stating that the apposition of isoprenoid units explains the biosynthesis of rubber, monoterpenes, sterols, triterpenes, and other natural products.

Mevalonic Acid

A $C_6$ acid ($3,5$ ext{-dihydroxy-}$3$ ext{-methylvaleric acid) discovered in 1956 that serves as a precursor in classical isoprenoid biosynthesis.

Isopentenyl Pyrophosphate (IPP)

The active $C_5$ isoprenoid building block formed from mevalonic acid pyrophosphate through decarboxylation and dehydration.

Biosynthesis of Isoprenoid Compounds

The multi-step pathway where $C_5$ isopentenyl pyrophosphate units are added to geranyl pyrophosphate ($C_{10}\text{PP}$) and farnesyl pyrophosphate ($C_{15}\text{PP}$) to yield squalene, steroids, carotenoids, and gutta.

1-Deoxy-D-xylulose-5-phosphate Pathway

A non-mevalonate pathway discovered in 1993 by M. Rohmer et al. that forms IPP via condensation of pyruvate and glyceraldehyde-3-phosphate, primarily located in plant plastids.

Secondary Metabolites

Plant-produced compounds derived from primary metabolic pathways that aid in survival and provide specific medicinal, culinary, or defensive traits.

Stress Compounds

Metabolites that accumulate to higher than normal levels in plants as a response to injury, frost, UV irradiation, dehydration, chemical treatment, or microbial infection.