Chemistry
Thaumatin is a protein which is isolated from katemfe fruit of west Africa (Thaumatococcus daniellii Benth). There may be several related proteins in the plant, but there are two main forms: thaumatin I and thaumatin II. Thaumatin I is composed of 207 amino acids, with molecular weight 22,204. Thaumatin II is synthesized as a precursor protein of 235 amino acids; the first 22 amino acids and the last 6 amino acids are apparently cleaved to produce a protein the same size as thaumatin I (207 amino acids) and 98% identical to thaumatin I. The complete amino acid sequences of thaumatin I and thaumatin II are available from the Swiss-Prot database. Thaumatins have an isoelectric point around 11-12. Their tertiary structures are maintained by 8 disulfide linkages.
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Discovery
According to van der Wel ("Developments in Food Proteins -- 4", B.J.F. Hudson, Ed., Elsevier Applied Science, London, 1986, pp. 219-245), the katemfe plant (also called "the miraculous fruit of the Sudan") is common in the West African rain forest zone. The fruit contains 1-3 black seeds surrounded by a gel, and capped with a membranous sac, the aril, which contains the sweet material. This is used as a sweetener in cooking, in flavoring palm wine, and in making confections for children.
Names
Thaumatin Talin
Taste
Thaumatin is sweet, with a slow onset, lingering sweetness and a licorice after-taste. Sweetness potency relative to sucrose is about 2000 x on a weight basis, and about 100,000 x sucrose on a molar basis.
© by D. Eric Walters