Types and Functions of Proteins (OpenStax Biology 2e)
Enzymes, which living cells produce, are catalysts in biochemical reactions (like digestion) and are usually complex or conjugated proteins. Each enzyme is specific for the substrate (a reactant that binds to an enzyme) upon which it acts. The enzyme may help in the breakdown, rearrangement, or synthesis reactions. We call enzymes that break down their substrates catabolic enzymes. Those that build more complex molecules from their substrates are anabolic enzymes, and enzymes that affect the rate of reaction are catalytic enzymes. Note that all enzymes increase the reaction rate and, therefore, are organic catalysts. An example of an enzyme is salivary amylase, which hydrolyzes its substrate amylose, a component of the starch.– What biomolecules perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells, and organisms, and transporting molecules from one location to another?
Hormones are chemical-signaling molecules, usually small proteins or steroids, secreted by endocrine cells that act to control or regulate specific physiological processes, including growth, development, metabolism, and reproduction. For example, insulin is a protein hormone that helps regulate the blood glucose level. The table above lists the primary types and functions of proteins.– What is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located three or four residues earlier along the protein sequence?
Proteins have different shapes and molecular weights. Some proteins are globular in shape; whereas, others are fibrous in nature. For example, hemoglobin is a globular protein, but collagen, located in our skin, is a fibrous protein. Protein shape is critical to its function, and many different types of chemical bonds maintain this shape. Changes in temperature, pH, and exposure to chemicals may lead to permanent changes in the protein’s shape, leading to loss of function, or denaturation. Different arrangements of the same 20 types of amino acids comprise all proteins. Two rare new amino acids were discovered recently (selenocystein and pirrolysine), and additional new discoveries may be added to the list.The first protein to be sequenced was insulin, by Frederick Sanger, in 1949. Sanger correctly determined the amino acid sequence of insulin, thus conclusively demonstrating that proteins consisted of linear polymers of amino acids rather than branched chains, colloids, or cyclols.
Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at: https://openstax.org/details/books/biology-2e
Research Article: Predicting Functions of Proteins in Mouse Based on Weighted Protein-Protein Interaction Network and Protein Hybrid Properties
Date Published: January 19, 2011 Publisher: Public Library of Science Author(s): Lele Hu, Tao Huang, Xiaohe Shi, Wen-Cong Lu, Yu-Dong Cai, Kuo-Chen Chou, Christos Ouzounis. http://doi.org/10.1371/journal.pone.0014556 Abstract: With the huge amount of uncharacterized protein sequences generated in the post-genomic age, it is highly desirable to develop effective computational methods for quickly and accurately predicting their functions. … Continue reading
Date Published: November 15, 2016 Publisher: Public Library of Science Author(s): Guohua Huang, Chen Chu, Tao Huang, Xiangyin Kong, Yunhua Zhang, Ning Zhang, Yu-Dong Cai, Alexey Porollo. http://doi.org/10.1371/journal.pone.0166580 Abstract: Although the number of available protein sequences is growing exponentially, functional protein annotations lag far behind. Therefore, accurate identification of protein functions remains one of the … Continue reading
Date Published: April 22, 2011 Publisher: Public Library of Science Author(s): Thomas Bourquard, Julie Bernauer, Jérôme Azé, Anne Poupon, Iddo Friedberg. http://doi.org/10.1371/journal.pone.0018541 Abstract: A protein-protein docking procedure traditionally consists of two successive tasks: a search algorithm generates a large number of candidate conformations mimicking the complex existing in vivo between two proteins, and a scoring function … Continue reading
Date Published: February 24, 2017 Publisher: Public Library of Science Author(s): Hafeez Ur Rehman, Nouman Azam, JingTao Yao, Alfredo Benso, Yong Deng. http://doi.org/10.1371/journal.pone.0171702 Abstract: The knowledge of protein functions plays an essential role in understanding biological cells and has a significant impact on human life in areas such as personalized medicine, better crops and improved … Continue reading