Natural Products and Small Biological Molecules

The complexes of hydrazine carboxylates with different noetals display various types of octahedral co-ordination, but all contain five-mmbered chelate rings (1) which are strictly analogous to the rings formed by a-amino-acids with the same metals. The analysis of calcium hydrazioecarboxylate 

L-Dopa (2), an amino-acid of current therapeutic interest, is believed to 

Whereas L-citrulline hydrochloride (4) is, like arginine, characterized by three planar groups which in this case are (a) the carboxyl group, (b) the side-chain, and (c) the urea function, with dihedral angles a b 91° and b c 87°, DL-ornithine hydrobromide (5) and Lay-diaminobutyric acid monohydrochloride (6) may be more simply represented by the two planes of 

L-Tyrosine-O-sulphate (10) is a constituent of both the human and porcine hormones gastrin and cholecystokininpancreozymin. In the di-hydrated potassium salt of this amino-acid derivative, the five-co-ordinate potassium ions are chelated both to the sulphate and carboxylate groups of the same molecule. The conformation about the C -Cp bond is syn rather 

Other amino-acids which have been studied include L-cysteic acid mono-hydrate,which is conformationally similar to L-cysteine and taurine, and (—)-2-aA o-amino-norbornane-2-carboxyllc acid hydrobromide which has been shown to have the absolute configuration (li , 2R, AS). DL-Tryptophan formate exhibits an anti conformation about the C -Cp bond, in contrast to the gauche arrangement observed in the hydrochloride. 

---

Before the advent of gene overexpression methods, small interfering RNA (siRNA) technologies, and other procedures to produce genetic knockout systems, natural products, and other biologically active small molecule-based compounds provided the first efficient means to probe cell biology. Natural toxins and... 

PYRROLE NATURAL PRODUCTS AND MATERIALS 5.2.4.1 Natural Products and Biologically Active Small Molecules... 

Natural Products and Biologically Active Small Molecules... 

---