See also: Glycan-protein interactions Ribbon diagram of a mouse antibody against cholera that binds a carbohydrate antigen Most microorganisms and plants can biosynthesize all 20 standard amino acids, while animals (including humans) must obtain some of the amino acids from the diet. [44] The amino acids that an organism cannot synthesize on its own are referred to as essential amino acids. Key enzymes that synthesize certain amino acids are not present in animals—such as aspartokinase, which catalyses the first step in the synthesis of lysine, methionine, and threonine from aspartate. If amino acids are present in the environment, microorganisms can conserve energy by taking up the amino acids from their surroundings and downregulating their biosynthetic pathways. a b c d e f g Murray RF, Harper HW, Granner DK, Mayes PA, Rodwell VW (2006). Harper's Illustrated Biochemistry. New York: Lange Medical Books/McGraw-Hill. ISBN 978-0-07-146197-9.

Bischoff TL, Voit C (1860). Die Gesetze der Ernaehrung des Pflanzenfressers durch neue Untersuchungen festgestellt (in German). Leipzig, Heidelberg. {{ cite book}}: CS1 maint: location missing publisher ( link) Martin, P D; Malley, D F; Manning, G.; Fuller, L. (Nov 1, 2002). "Determination of soil organic carbon and nitrogen at the field level using near-infrared spectroscopy". Canadian Journal of Soil Science. 82 (4): 413–422. doi: 10.4141/S01-054. Harold H (1951). "Origin of the Word 'Protein.' ". Nature. 168 (4267): 244. Bibcode: 1951Natur.168..244H. doi: 10.1038/168244a0. PMID 14875059. S2CID 4271525.Roohi, Bano K, Kuddus M, Zaheer MR, Zia Q, Khan MF, Ashraf GM, Gupta A, Aliev G (2017). "Microbial Enzymatic Degradation of Biodegradable Plastics". Current Pharmaceutical Biotechnology. 18 (5): 429–440. doi: 10.2174/1389201018666170523165742. PMID 28545359.

Ardejani MS, Powers ET, Kelly JW (August 2017). "Using Cooperatively Folded Peptides To Measure Interaction Energies and Conformational Propensities". Accounts of Chemical Research. 50 (8): 1875–1882. doi: 10.1021/acs.accounts.7b00195. PMC 5584629. PMID 28723063. protein, highly complex substance that is present in all living organisms. Proteins are of great nutritional value and are directly involved in the chemical processes essential for life. The importance of proteins was recognized by chemists in the early 19th century, including Swedish chemist Jöns Jacob Berzelius, who in 1838 coined the term protein, a word derived from the Greek prōteios, meaning “holding first place.” Proteins are species-specific; that is, the proteins of one species differ from those of another species. They are also organ-specific; for instance, within a single organism, muscle proteins differ from those of the brain and liver. Strümpfer J, Schulten K (2012). "Open Quantum Dynamics Calculations with the Hierarchy Equations of Motion on Parallel Computers". J. Chem. Theory Comput. 8 (8): 2808–2816. doi: 10.1021/ct3003833. PMC 3480185. PMID 23105920.

Yuste R (December 2005). "Fluorescence microscopy today". Nature Methods. 2 (12): 902–4. doi: 10.1038/nmeth1205-902. PMID 16299474. S2CID 205418407. Walian P, Cross TA, Jap BK (2004). "Structural genomics of membrane proteins". Genome Biology. 5 (4): 215. doi: 10.1186/gb-2004-5-4-215. PMC 395774. PMID 15059248.

a b Case LP, Daristotle L, Hayek MG, Raasch MF (2010). Canine and Feline Nutrition-E-Book: A Resource for Companion Animal Professionals. Elsevier Health Sciences. Mariotti F, Gardner CD. Dietary protein and amino acids in vegetarian diets—a review. Nutrients. 2019;11(11):2661. doi:10.3390/nu11112661 Wu L, Candille SI, Choi Y, Xie D, Jiang L, Li-Pook-Than J, Tang H, Snyder M (July 2013). "Variation and genetic control of protein abundance in humans". Nature. 499 (7456): 79–82. Bibcode: 2013Natur.499...79W. doi: 10.1038/nature12223. PMC 3789121. PMID 23676674. Proteins are the chief actors within the cell, said to be carrying out the duties specified by the information encoded in genes. [28] With the exception of certain types of RNA, most other biological molecules are relatively inert elements upon which proteins act. Proteins make up half the dry weight of an Escherichia coli cell, whereas other macromolecules such as DNA and RNA make up only 3% and 20%, respectively. [44] The set of proteins expressed in a particular cell or cell type is known as its proteome. Pauling L, Corey RB (May 1951). "Atomic coordinates and structure factors for two helical configurations of polypeptide chains" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 37 (5): 235–40. Bibcode: 1951PNAS...37..235P. doi: 10.1073/pnas.37.5.235. PMC 1063348. PMID 14834145. Archived (PDF) from the original on 2012-11-28 . Retrieved 2009-04-14.Sanger F (1949). "The terminal peptides of insulin". The Biochemical Journal. 45 (5): 563–74. doi: 10.1042/bj0450563. PMC 1275055. PMID 15396627. Quaternary structure: the structure formed by several protein molecules (polypeptide chains), usually called protein subunits in this context, which function as a single protein complex. Legumes—such as beans, lentils, and peas—are high in protein and contain many essential amino acids. (more) Muñoz-Huerta, Rafael F.; Guevara-Gonzalez, Ramon G.; Contreras-Medina, Luis M.; Torres-Pacheco, Irineo; Prado-Olivarez, Juan; Ocampo-Velazquez, Rosalia V. (Aug 16, 2013). "A Review of Methods for Sensing the Nitrogen Status in Plants: Advantages, Disadvantages and Recent Advances". Sensors. 13 (8): 10823–10843. Bibcode: 2013Senso..1310823M. doi: 10.3390/s130810823. PMC 3812630. PMID 23959242. Proteins were first described by the Dutch chemist Gerardus Johannes Mulder and named by the Swedish chemist Jöns Jacob Berzelius in 1838. [2] [3] Mulder carried out elemental analysis of common proteins and found that nearly all proteins had the same empirical formula, C 400H 620N 100O 120P 1S 1. [4] He came to the erroneous conclusion that they might be composed of a single type of (very large) molecule. The term "protein" to describe these molecules was proposed by Mulder's associate Berzelius; protein is derived from the Greek word πρώτειος ( proteios), meaning "primary", [5] "in the lead", or "standing in front", [6] + -in. Mulder went on to identify the products of protein degradation such as the amino acid leucine for which he found a (nearly correct) molecular weight of 131 Da. [4] Prior to "protein", other names were used, like "albumins" or "albuminous materials" ( Eiweisskörper, in German). [7]

Davey NE, Van Roey K, Weatheritt RJ, Toedt G, Uyar B, Altenberg B, Budd A, Diella F, Dinkel H, Gibson TJ (January 2012). "Attributes of short linear motifs". Molecular BioSystems. 8 (1): 268–81. doi: 10.1039/c1mb05231d. PMID 21909575. Mendive-Tapia D, Mangaud E, Firmino T, de la Lande A, Desouter-Lecomte M, Meyer HD, Gatti F (2018). "Multidimensional Quantum Mechanical Modeling of Electron Transfer and Electronic Coherence in Plant Cryptochromes: The Role of Initial Bath Conditions". J. Phys. Chem. B. 122 (1): 126–136. doi: 10.1021/acs.jpcb.7b10412. PMID 29216421.Stepanenko OV, Verkhusha VV, Kuznetsova IM, Uversky VN, Turoverov KK (August 2008). "Fluorescent proteins as biomarkers and biosensors: throwing color lights on molecular and cellular processes". Current Protein & Peptide Science. 9 (4): 338–69. doi: 10.2174/138920308785132668. PMC 2904242. PMID 18691124.