Sandbox-insulin-ben

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קורס חלבונים מבנה וקישור תכנית רוטשילד ויצמן

מרצה:שירלי דאובה
Image:SHIRLEY_DAUBE.jpg

Contents

מבנה הקורס

283px|thumb|Structure of the protein 1EFN

מבנה ראשוני של חלבון

Image:Pb.png



קישור למצגת הקורס

In biochemistry, the primary structure of a biological molecule is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including stereochemistry). For a typical unbranched, un-crosslinked biopolymer (such as a molecule of DNA, RNA, or typical intracellular protein), the primary structure is equivalent to specifying the sequence of its monomeric subunits, e.g., the nucleotide or peptide sequence.

Primary structure is sometimes mistakenly termed primary sequence, but there is no such term, as well as no parallel concept of secondary or tertiary sequence. By convention, the primary structure of a protein is reported starting from the amino-terminal (N) end to the carboxyl-terminal (C) end, while the primary structure of DNA or RNA molecule is reported from the 5' end to the 3' end.

The primary structure of a nucleic acid molecule refers to the exact sequence of nucleotides that comprise the whole molecule. Frequently, the primary structure encodes motifs that are of functional importance. Some examples of sequence motifs are: the C/D[1] and H/ACA boxes[2] of snoRNAs, Sm binding site found in spliceosomal RNAs such as U1, U2, U4, U5, U6, U12 and U3, the Shine-Dalgarno sequence,[3] the Kozak consensus sequence[4] and the RNA polymerase III terminator.[5]

מבנה שניוני של חלבון

Image:123.png size=250px 250px|thumb|right|alt = Colored dice with checkered background|Secondary (inset) and tertiary structure of tRNA demonstrating coaxial stacking. PDB ([http://www.ncbi.nlm.nih.gov/pubmed/357742?dopt=Abstract 6tna]) rendered via [http://pymol.sourceforge.net PyMOL].

In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids (DNA/RNA). It does not, however, describe specific atomic positions in three-dimensional space, which are considered to be tertiary structure. Secondary structure is formally defined by the hydrogen bonds of the biopolymer, as observed in an atomic-resolution structure. In proteins, the secondary structure is defined by patterns of hydrogen bonds between backbone amide and carboxyl groups (sidechain-mainchain and sidechain-sidechain hydrogen bonds are irrelevant), where the DSSP definition of a hydrogen bond is used. In nucleic acids, the secondary structure is defined by the hydrogen bonding between the nitrogenous bases.

For proteins, however, the hydrogen bonding is correlated with other structural features, which has given rise to less formal definitions of secondary structure. For example, in general residues in protein helices adopt backbone dihedral angles in a particular region of the Ramachandran plot; thus, a segment of residues with such dihedral angles is often called a "helix", regardless of whether it has the correct hydrogen bonds. Many other less formal definitions have been proposed, often applying concepts from the differential geometry of curves, such as curvature and torsion. Structural biologists solving a new atomic-resolution structure will sometimes assign its secondary structure "by eye" and record their assignments in the corresponding PDB file.

The secondary structure of a nucleic acid molecule refers to the basepairing interactions within a single molecule or set of interacting molecules. The secondary structure of biological RNA's can often be uniquely decomposed into stems and loops. Frequently, these elements, or combinations of them, can be further classified, for example, tetraloops, pseudoknots and stem-loops. There are many secondary structure elements of functional importance to biological RNA's; some famous examples are the Rho-independent terminator stem-loops and the tRNA cloverleaf. There is a minor industry of researchers attempting to determine the secondary structure of RNA molecules. Approaches include both experimental and computational methods (see also the List of RNA structure prediction software).

מבנה שלישוני של חלבון

חלק 1

חלק 2

חלק3

מבנה רביעוני

קואופרטיביות ואלוסטריה והסיפור של המוגלובין

קביעת מבנה - שיטות לאנליזה של חלבונים

סיפור האינסולין

Human insulin chain A (grey) and chain B (green), 3i40

Drag the structure with the mouse to rotate
For additional details see Insulin Structure & Function.

3D structures of Insulin (Updated on 11-June-2015)

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