They serve as an energy source during prolonged fasting, diabetes, and when the diet is rich in proteins.
creatine, citrulline, carnitine), the oxygen-binding molecule ‘ heme‘, and DNA bases called purines. the allergy mediator histamine), energy-related metabolites (e.g. dopamine, serotonin, GABA, epinephrine), local mediators (e.g.
They serve as precursors for many biologically active molecules, such as neurotransmitters (e.g.
For more details on these remarkable molecules see this section.
They are the principle building blocks of proteins, Nature’s most functionally diverse biomolecules.
Some of the figures are taken from other sources, such as Lehninger’s Principles of Biochemistry, 5th edition textbook.Īmino acids are small organic molecules that play several important roles in living organisms: The book discusses protein structure & function while referring to many everyday applications of protein science, such as disease & cure, drugs of abuse, toxins, industrial engineering and much more. Nir Ben-Tal and I wrote, Introduction to Proteins: Structure, Function, & Motion: It is adapted in most part from the book Prof. Therefore, this research will be instructive for the rational design and modification of efficient vehicle peptides for cytosolic delivery of macromolecular therapeutics for biomedical application in the future.The summery below is for educational purposes only. Furthermore, numerous protein targets, including mutated tumor suppressors, overexpressed oncogenic proteins, were considered “undruggable” by small molecule inhibitors. It is evaluated that 75% of the human proteome is intracellular and unapproachable to protein therapeutics like a monoclonal antibody. Hao Fei, Professor, Suzhou Institute of Nano-tech and Nano-Bionics, Chinese Academy of Sciences The resultant peptide LP6 has the required and adequate hydrophobicity to endue its helical and aggregation capability in the acidic endosomal environment, and can drastically facilitate cargo cell entry and cytosolic delivery of macromolecules like protein toxin and dextran.įrom the reductionist point of view, the study used the simplest natural proteinogenic amino acids and the most essential structures of peptide, thus our finding may represent a structure-function relationship that is fundamental.” The two actions are attaching themselves to the cell membrane without resulting in cell death, and developing peptide assembled holes in the acidic endosomal membrane to facilitate cargo entry. The scientists balanced the two major actions of the peptide by the hydrophobicity-tuning strategy.
Each person has their own unique “fingerprint” of protein activity, says study.
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This is due to the numerous amine-containing amino acids in their sequences and these cationic groups are drawn to the negatively charged sialic acids (a kind of sugar) and acidic phospholipids mostly seen in the cell membrane, however greatly enriched in endosomal membranes. These peptides are positively charged or “cationic”. The polar end aids the peptide to persist as water-soluble and later develop helical shapes to create holes in the membranes. The greasy end facilitates the insertion of the peptide into membranes. These peptides normally called “amphipathic peptide”, have both polar (water-attracting or hydrophilic) and greasy (water-repelling or hydrophobic) ends. The researchers employed a strategy of hydrophobicity-tuning on a set of artificial peptides and found an optimized peptide specifically responsive to the acidic environment on the endosomal membrane. The study was headed by Professor Hao Fei from the Suzhou Institute of Nano-tech and Nano-Bionics of the Chinese Academy of Sciences. The research was published in the Journal of Biological Chemistry. This facilitates cargos-like proteins to be delivered into the cytoplasm and at the same time, leaves the plasma membrane intact. Recent research reported that a peptide that can securely open up an endosomal membrane. The cell plasma membrane and the derived endosomal membranes are both greasy barriers that prevent the inflow of water-soluble macromolecules like nucleic acids and proteins into cells.īreaking “doors” on the plasma membrane directly can destroy the cell easily, however opening inner “doors” on the endosomal membrane was proven to be difficult, despite being safe.