A comparison of the Hoesch and the Watson-Schwartz tests shows that the latter, although slightly more complicated, generally yields more concise results and is superior in sensitivity and specificity for porphobilinogen. The recommendation of the Hoesch test for use as a "bedside screening" method seems unrealistic. Before the diagnosis of an "inducible" porphyria is made, a positive Hoesch te...

Cycloheximide inhibits polar indoleacetic acid transport in midrib tissues of leaves of citrus (Citrus sinensis [L.] Osbeck) and poplar (Populus deltoides Bartr.) as measured by the donor-receiver agar cylinder technique. It appears that the mechanism of auxin transport inhibition by cycloheximide consists in arresting protein synthesis and not in the disruption of energy flow. The interpretati...

d-Tryptophan was converted to l-tryptophan in tissue cultures of tobacco, in whole cells treated with dimethylsulfoxide, and in cell-free extracts treated by Sephadex G-25 filtration. Evidence was obtained that tryptophanase, tryptophan pyrrolase, and transaminase activities were not involved. The data were best explained by the presence of a tryptophan racemase as the enzyme catalyzing the rea...

Commercial zein was base-hydrolyzed and purified extracts were subjected to gas chromatography-selected ion monitoring-mass spectrometry analysis. Indoleacetic acid (IAA) was shown to be released from this storage protein of corn (Zea mays). Isotope dilution using [(13)C(6)]IAA as an internal standard revealed a conservative ratio of 1 mole IAA to 175 moles zein. Immunoelectron micrographs of i...