CHAPTER 17 – NEW AND UNIDENTIFIED GROWTH FACTORS

Publisher Summary This chapter discusses the new and unidentified growth factors of lipoic acid, carnitine, peptides, ubiquinone, lyxoflavin, andcoenzyme III. Studies on the probable role of lipoic acid in metabolism have clustered about two closely related, although different, conditions, that is, those that involve the free vitamin added to systems in substrate amounts and others that involve purified enzyme systems, in which the lipoic acid came largely from natural sources. Lipoic acid plays a part in the primary quantum conversion act of photosynthesis. Carnitine is different from almost all other vitamins. Three general types of methods are developed for the assay of carnitine: (1) biological method, (2) chemical method, and (3) enzymatic method. Carnitine is isolated from meat extract since this material constitutes one of the richest known sources of the compound. Attempts to ascertain the presence of bound carnitine in a wide array of tissues have met with the usual uncertainties associated with methods of isolation and determination.