Simple methods for determination of methionine and cystine in legume seeds

✍ Scribed by Hedwig E. Herrick; John M. Lawrence; David R. Coahran

• Publisher: Elsevier Science
• Year: 1972
• Tongue: English
• Weight: 715 KB
• Volume: 48
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(72)90087-5

✦ Synopsis

Peas, beans, and lentils are very good sources of protein for animal and human nutrition but are deficient in the essential sulfur-containing amino acids, methionine and cystine (l-3). Screening methods for the determination of these amino acids are of prime importance to breeding programs undertaken to improve the nutritional quality of pea, bean, and lentil varieties.

After trying to adapt existing methods (4,s) for methionine analysis to legumes and finding them unsuitable for an inexpensive, reliable screening method, a procedure combining ascending thin-layer chromatography and densitometry was worked out. The main part of this report describes this procedure in detail. It was found t,hat a calorimetric procedure involving an adaptation and clarification of the method of Goa (6) gives satisfactory results for cystine plus cysteine. This method is discussed more briefly. Using these two methods, one can analyze numerous legume varieties and choose for breeding purposes those with the most favorable composition.

METHIONINE DETERMINATION

Reagents and Apparatus

Thin-layer plates. Precoat,ed silica gel plates made by E. Merck AG, Darmstadt, purchased from Brinkmann Instruments, Inc. The coating on these 20 X 20 cm plates is 0.25 mm thick and contains no fluorescent indicator.