The structure of orthorhombic crystals of monellin, a sweet protein extracted from African serendipity berries, has been solved by molecular replacement and refined to 2.3 A resolution. The final R factor was 0.150 for a model with excellent geometry. A monellin molecule consists of two peptides that are non-covalently bound, with chain A composed of three beta-strands interconnected by loop regions and chain B composed of two beta-strands interconnected by an alpha-helix. The N terminus of chain A is in close proximity to the C terminus of chain B. The two molecules in the asymmetric unit are related by a non-crystallographic twofold axis and form a dimer, similar to those previously observed in other crystal forms of both natural and single-chain monellin. The r.m.s, deviation between the Calpha atoms in the two independent molecules is 0.60 A, while the deviations from the individual molecules in the previously reported monoclinic crystals are 0.50-0.57 A. This result proves that the structure of monellin is not significantly influenced by crystal packing forces.
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http://dx.doi.org/10.1107/S0907444997006860 | DOI Listing |
Int J Biol Macromol
January 2024
Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant'Angelo, Via Cintia, 80126 Naples, Italy. Electronic address:
Protein fibrillation is commonly associated with pathologic amyloidosis. However, under appropriate conditions several proteins form fibrillar structures in vitro that can be used for biotechnological applications. MNEI and its variants, firstly designed as single chain derivatives of the sweet protein monellin, are also useful models for protein fibrillary aggregation studies.
View Article and Find Full Text PDFFood Chem
May 2024
Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, PR China. Electronic address:
Sweet proteins offer a promising solution as sugar substitutes by providing a sugar-like sweetness without the negative health impacts linked to sugar or artificial sweeteners. However, the low thermal stability of sweet proteins has hindered their applications. In this study, we took a computational approach utilizing ΔΔG calculations in PyRosetta to enhance the thermostability of single-chain monellin (MNEI).
View Article and Find Full Text PDFJ Biomol Struct Dyn
December 2023
Molecular Modelling and Simulation Laboratory, Department of Molecular Biology and Biotechnology, Tezpur University, Assam, India.
Intrinsically disordered proteins (IDPs) are proteins that do not form uniquely defined three-dimensional (3-D) structures. Experimental research on IDPs is difficult since they go against the traditional protein structure-function paradigm. Although there are several predictors of disorder based on amino acid sequences, but very limited based on the 3-D structures of proteins.
View Article and Find Full Text PDFProtein J
December 2023
School of Pharmaceutical Sciences, Okayama University, Okayama, Japan.
Single-chain monellin (SCM) is an engineered protein that links the two chains of monellin, a naturally sweet-tasting protein. This protein is an attractive candidate for use as a sugar replacement in food and beverages and has numerous other applications. Therefore, generating SCM mutants with improved stability is an active area of research to broaden the range of its potential applications.
View Article and Find Full Text PDFFoods
May 2023
CBIOS (Research Center for Biosciences and Health Technologies), Universidade Lusófona de Humanidades e Tecnologias, Campo Grande 376, 1749-024 Lisboa, Portugal.
Recently, customers have been keener to buy products manufactured using all-natural ingredients with positive health properties, but without losing flavor. In this regard, the objective of the current study is to review the consumption of brazzein and monellin, their nutritional profiles and health effects, and their potential applications in the food industry. This poses challenges with sustainability and important quality and safety indicators, as well as the chemical processes used to determine them.
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