The formation of lysinoalanine (LAL) in casein, zein, and wheat gluten was studied in relation to varied levels of alkali, added cysteine, and added lysine. Protein suspensions were heated in alkali, subjected to acid hydrolysis conditions, and then analyzed for LAL using high-pressure liquid chromatography. Cysteine generally decreased LAL formations while lysine decreased formation in casein and increased the LAL level in zein and gluten. In a separate experiment, samples of normal and high lysine corn varieties were heated in a calcium hydroxide solution. Low levels o f LAL were formed (200-217 ppm) but there was no significant difference between the two varieties in the amount of LAL found. Lysine fortification of the normal corn did not increase LAL formation. The addition of cysteine to high lysine corn caused increased levels of LAL.
The use of high pressure liquid chromatography (HPLC) to determine the lysinoalanine (LAL) content in protein hydrolysates was investigated. The dansyl derivative of LAL was formed by reacting protein hydrolysates with dansyl chloride and HPLC was used to separate and quantify nanogram quantities of LAL. An excess level of dansyl chloride was necessary to form a consistent derivative peak for chromatographic analysis. Mass spectrometry was used to analyze the LAL derivative in a casein hydrolysate but a definitive spectrum was not obtained. The HPLC procedure for LAL was found to be less variable than a thin-layer chromatographic technique and has potential for use as a rapid method for the analysis of LAL in food proteins.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.