Purification and Characterization of the Methionine-Rich 2S Seed Proteins from the Brazil Nut Family (Lecythidaceae)

Abstract

2S seed proteins were purified from paradise nut (Lecythis zabucajo) and cannonball (Couroupita quianensis), two members of the Brazil nut family (Lecythidaceae). The amino acid composition, subunit structure, partial protein sequence, immunoreactivity, and processing pattern of these proteins were determined. The 2S proteins from both paradise nut (PN2S) and cannonball (CB2S) are rich in the sulfur amino acids, especially methionine (Met): 14.0% Met and 4.3% cysteine (Cys) in PN2S; 19.9% Met and 4.5% Cys in CB2S. Both 2S proteins are synthesized as a precursor polypeptide of 18 kDa and processed stepwise to form the 9- and 3-kDa mature subunit polypeptides. These properties are similar to those of the Brazil nut (Bertholletia excelsa H.K.B.) 2S protein (BN2S). However, while the 18-kDa precursor polypeptide of PN2S, like that of BN2S, undergoes three sequential cleavages to form the two mature subunits, only two stepwise cleavages occur during the processing of CB2S. Keywords: Met-rich protein; 2S protein; seed proteins; Brazil nut

Functionality of Succinylated Brazil Nut (Bertholletia excelsa HBK) Kernel Globulin

“…Normally defective and undersized nut kernel, which do not satisfy export standards are sold at very cheap prices to oil expelling industries. The defatted cake, in spite of containing about 46.0% protein (Ramos and Bora, 2003) rich in sulphur containing amino acids [9] is used to a limited extent as an ingredient in animal rations. One of the possible approaches to substantiate its worth under explored commodity is to transform it into protein isolate and utilise for nutritional and/or functional improvement of food products.…”

Functional characterization of acetylated Brazil nut (Bertholletia excelsa HBK) kernel globulin

“…The broken, damaged or deformed nut kernels are sold at a very low price and are utilized principally by small-scale oil industries. The defatted kernel flour, in spite of being rich source of sulfur containing amino acids [24] is presently used in animal feed formulations. Assessment of the functional properties of Brazil nut kernel globulin may be helpful to evaluate its use in food formulations.…”

“…Information on fractionation and characterization of Brazil nut kernel proteins [21], methionine rich 2S fraction [24] and N-terminal amino acids of 7S fraction [3] and functional properties of protein isolate and concentrate [6] are available. However, there seems a lack of data on the functionality of chemically modified Brazil nut kernel globulin in scientific literature.…”

Seed Composition of Amazonian Lecythidaceae Species: Part 3 in the Series “Studies of Edible Amazonian Plants”

“…The seeds are considered as edible, their taste is agreeable, but very little is known about their composition. Recently, Zuo and Sun (1996) reported a remarkable high content of methionine in the 2S protein of that seed. Unfortunately, only a part of the planned analyses could be performed because only a very small amount of seeds of that species had been available.…”