【文章內(nèi)容簡介】 e Prediction PROTEIN ? Protein: A large molecule posed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein. ? Proteins are required for the structure, function, and regulation of the body39。s cells, tissues, and ans. Each protein has unique functions. Proteins are essential ponents of muscles, skin, bones and the body as a whole. ? Protein is one of the three types of nutrients used as energy sources by the body, the other two being carbohydrate and fat. Proteins and carbohydrates each provide 4 calories of energy per gram, while fats produce 9 calories per gram. ? The word protein was introduced into science by the great Swedish physician and chemist J246。ns Jacob Berzelius (17791848) who also determined the atomic and molecular weights of thousands of substances, discovered several elements including selenium, first isolated silicon and titanium, and created the present system of writing chemical symbols and reactions. Helsinki University of Technology 22 DNA, RNA, Protein Structure Prediction Tools for PROTEIN Structure Prediction: ExPASy ? The ExPASy (Expert Protein Analysis System) proteomics server from the Swiss Institute of Bioinformatics (SIB) is dedicated to molecular biology with an emphasis on data relevant to allows you to browse through a number of databases produced in Geneva, such as SwissProt, PROSITE, SWISS2DPAGE, SWISS3DIMAGE, ENZYME, as well as other crossreferenced databases (such as EMBL/GenBank/DDBJ, OMIM, Medline, FlyBase, ProDom, SGD, SubtiList, etc). ? It also allows access to many analytical tools for the identification of proteins, the analysis of their sequence and the prediction of their tertiary structure. ExPASy also offers you many documents relevant to these field of research and you will find from the servers, links to most relevant sources of information across the 2DService is a nonprofit 2D PAGE service to the scientific munity ? ExPASy was created in August 1993, it was one of the first WWW servers for biological sciences. Since that date it has undergone constant modifications and improvements. Helsinki University of Technology 23 DNA, RNA, Protein Structure Prediction Helsinki University of Technology 24 DNA, RNA, Protein Structure Prediction Pa ra ve r e st a p e l韈 u l a , d e b ed i sp o n e r d e Q u ick T ime ? y d eu n d e s co mp re so r T I F F ( si n co mp ri m ir) .Pa ra ve r e st a p e l韈 u l a , d e b ed i sp o n e r d e Q u ick T ime ? y d eu n d e sco mp re so r T I F F (si n co mp ri mi r) .Helsinki University of Technology 25 DNA, RNA, Protein Structure Prediction PROSITE Database of protein families and domains ? PROSITE is a database of protein families and domains. ? It consists of biologically significant sites, patterns and profiles that help to reliably identify to which known protein family (if any) a new sequence belongs. ? It is based on the observation that, while there is a huge number of different proteins, most of them can be grouped, on the basis of similarities in their sequences, into a limited number of families. ? Proteins or protein domains belonging to a particular family generally share functional attributes and are derived from a mon is apparent, when studying protein sequence families, that some regions have been better conserved than others during evolution. Helsinki University of Technology 26 DNA, RNA, Protein Structure Prediction ? These regions are generally important for the function of a protein and/or for the maintenance of its three dimensional structure. By analyzing the constant and variable properties of such groups of similar sequences, it is possible to derive a signature for a protein family or domain, which distinguishes its members from all other unrelated proteins. ? A pertinent analogy is the use of fingerprints by the police for identification purposes. A fingerprint is generally sufficient to identify a given individual. Similarly, a protein signature can be used to assign a newly sequenced protein to a specific family of proteins and thus to formulate hypotheses about its function. ? PROSITE currently contains patterns and profiles specific for more than a thousand protein families or domains. Each of these signatures es with documentation providing background information on the structur