Molecules, Vol. 28, Pages 6556: Ginsentide-like Coffeetides Isolated from Coffee Waste Are Cell-Penetrating and Metal-Binding Microproteins

Molecules, Vol. 28, Pages 6556: Ginsentide-like Coffeetides Isolated from Coffee Waste Are Cell-Penetrating and Metal-Binding Microproteins Molecules doi: 10.3390/molecules28186556 Authors: James P. Tam Jiayi Huang Shining Loo Yimeng Li Antony Kam Coffee processing generates a huge amount of waste that contains many natural products. Here, we report the discovery of a panel of novel cell-penetrating and metal ion-binding microproteins designated coffeetide cC1a–c and cL1–6 from the husk of two popular coffee plants, Coffea canephora and Coffea liberica, respectively. Combining sequence determination and a database search, we show that the prototypic coffeetide cC1a is a 37-residue, eight-cysteine microprotein with a hevein-like cysteine motif, but without a chitin-binding domain. NMR determination of cC1a reveals a compact structure that confers its resistance to heat and proteolytic degradation. Disulfide mapping together with chemical synthesis reveals that cC1a has a ginsentide-like, and not a hevein-like, disulfide connectivity. In addition, transcriptomic analysis showed that the 98-residue micrcoproten-like coffeetide precursor contains a three-domain arrangement, like ginsentide precursors. Molecular modeling, together with experimental validation, revealed a Mg2+ and Fe3+ binding pocket at the N-terminus formed by three glutamic acids. Importantly, cC1a is amphipathic with a continuous stretch of 19 apolar amino acids, which...
Source: Molecules - Category: Chemistry Authors: Tags: Article Source Type: research