Abstract
Publisher Summary This chapter discusses the importance of intermediates in histidine breakdown. Urocanic acid can be determined by its absorption in the ultraviolet region or colorimetrically after coupling with diazotized 4-nitroaniline. It is found that with most biological materials, such as urine, numerous interfering materials are present which have to be eliminated by a preliminary purification. One milliliter of urine is placed in a conical centrifuge tube and thoroughly mixed with 5 ml of absolute ethanol. It is found that to increase the specificity of the method, aliquots of the eluate can be treated with urocanase, and the decrease in optical density measured. The amount of urocanic acid is calculated from the decrease in optical density in the incubated sample. The support for the presence of urocanic acid can be obtained by comparing the spectra of the incubated and the nonincubated samples and the difference spectra should be similar to that of urocanic acid. Formiminoglutamic acid is labile to alkali and produces NH 3 , HCOOH, and glutamic acid on hydrolysis. It is observed that the quantitative analysis of formylglutamic acid can be carried out by the reduced ninhydrin method.
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