Core Structure Of Proteins

They are known to be the workhorses of the body cell that carries out diverse catalytic and structural roles into building the structures of all living organisms [15]. The basic structure of protein is a chain of amino acids that supplies energy to a body. There are 20 different naturally occurring amino acids that make all types of protein. Proteins come in various sizes and shapes. Some comes in a thread-like shape known as fibrous proteins and they tend to have structural or mechanical roles. Others come in spherical shapes, known as the globular proteins [16]. These spherical proteins function as enzymes, transport proteins, or antibodies. The key function of protein is based on its ability to recognize and bind specific ally to molecules, it also need to be in the right shape in other to function properly [15]. The primary structure of proteins is a linear sequence of amino acids encoded by DNA. This sequence controls how protein folds into three dimensional structure, the stability of its resulting structure [17], and functions. It is important to add that protein is an important building block of bones, skin, blood and

Skeletal muscle contractions play a pivotal role in our day-to-day lives. Their main function is to generate force and provide our bodies with structural integrity. For many of us, muscle contractions seem effortless, but there’s actually quite a bit going on under the surface. Our muscles are composed of sarcomeres, units of skeletal muscle fibers, which are made up of actin and myosin contractile filaments. These filaments need to bind to each other in order to lengthen and shorten the sarcomere. However, the binding sites for actin and myosin are blocked by troponin and tropomyosin proteins. In order to get them off of the binding sites, calcium needs to bind to the troponin, which then lifts

Myosin head pivots and moves the thin filament closer to the M line (center structure of the H zone) proteins as the thick filament slides past

Muscle contains two type of important proteins which are myosin for thick filament and actin for the thin filament. The types of muscle can be categorized as skeletal muscle: attached directly or indirectly to the skeleton, smooth muscle: nonstriated appearance and no ordered myofibrils, and cardiac muscle: muscle of the hard with presence of intercalated disks. The process of myogenesis, forms tubular muscle cells which are myocytes (muscle fibers or myofibers) in skeletal muscle. Myofibers contain myofibrils, composed of repeating sections of sarcomeres.

The three myofilaments, the thick filaments, the thin filaments, and the elastic filaments, are the microfilaments that comprise the myofibril. The thick filament is made of many myosin molecules with a dual-globular head and a short, stubby tail. On the other hand, the thin filament is made of many inter-woven strands of fibrous actin with molecules of fibrous tropomyosin distributed along the thin filament. Each tropomyosin molecule has a troponin complex that can bind calcium ions, and upon calcium binding, it induces a conformational change within tropomyosin that exposes the myosin-binding sites on the actin filaments. Elastic filaments are made of titin that is attached to the Z disc weaves through the center of thick filament (Martini, Nath, and Bartholomew, 283-287).

They have used Schizosaccharomyces pombe as a model because it divides by contractile ring during yeast fission and the using of live cell microscopy is easier comparing to other species. They proved that contraction of CR of Schizosaccharomyces pombe is dependent on myosin II rather than actin

Titin (TTN), the largest known protein and the third most abundant type of filament together with actin and myosin, plays an important role in both skeletal and cardiac muscle. Consisting of 364 exons and located on chromosome 2q31, TTN is highly repetitive and complex. TTN has many functions such as acting as an architectural protein, providing attachment to many proteins, acting a molecular blueprint for thick filament assembly, holding the sarcomere in place during contractionss, allowing force transmission at the Z line and maintaining the resting tension in the I band. TTN is composed of four functional regions: Z amino terminal Z line, the I-band, A-band regions and the carboxy terminal M-line. The Z-line secures the TTN to the sarcomeric Z-disk by binding to multiple proteins. The I band consists of highly repetitive domains that act as a molecular spring that gives TTN its elasticity and capability to maintain its Z- and M- line connections during muscle elongation and contraction. Variations in the I band can lead to shortening of TTN that can lead to increased muscle stiffness. The A band interacts with myosin to stabilize and ensure the correct assembly of the thick filament. The M-line regulates TTN expression and turnover number.

Proteins are large complex molecules that have many roles in the human body, as well as other organisms. It is made of hundreds of small monomers called amino acids that when combined produces a unique 3-dimensional structure to serve a specific function/purpose. A protein has several functions from the transportation of oxygen in the body e.g. haemoglobin to just as simple as an enzyme e.g. maltase to break down maltose.

The dystrophin protein, found inside of muscle cells, links the intracellular actin with the dystrophin-associated protein complex on the cell membrane, which is anchored to the extracellular matrix outside the muscle cell membrane (fig 5).

From figure 1 it is evident that proteins solidify at different temperatures. As the temperature rises the isometric force generated by the myosin head which is an endothermic reaction also increases this was evident when we observed the first mild shortening of the muscle around 39°C which was an isotonic contraction because the muscle shorten even when the force was constant. But as we increased the temperature the myosin solidified at 40°C as seen from figure 1 which correlates with. (Bing et al, 2008). This is greatly because myosin is an unstable protein which uses ATPase an enzyme that maneuver’s along actin molecules to hydrolyze ATP to power the movement of the myosin head. By increasing the temperature the enzyme loses its structure or binding site therefore cannot perform its function.

All organisms, from humans to simple bacteria, have a necessity to move in order to adapt to changes in their external or internal environment, navigate towards food, and avoid dangers. Even cells are teeming with motion as they reorganize organelles, nucleic acids, and proteins. At the molecular level, two types of elements assist in the control movements of the cell and the organism as a whole: molecular-motor proteins and intricate complexes of protein filaments that make up the cytoskeleton of the cell (Vale and Milligan, 2000). Myosin is a family of motor protein that act as enzymes in the hydrolysis of adenosine triphosphate (ATP) to form adenosine diphosphate (ADP) and inorganic phosphate (Pi), The energy released by this reaction to drive the movement of molecules and contraction of muscle fibers (Grigorenko et al., 2007). A remarkable part of evolution is that the same mechanisms that control of contraction of muscles by myosin, are also used to propel

The specific and unique order in the polypeptide chain is determined by the information from the cellular genetic code of the protein. Having one amino acid in the structure causes the amino acid to not function properly or at all. There are four levels of protein structures, the primary structure, secondary structure, tertiary structure, and quaternary structure. The primary structure explains the order of which the twenty amino acids in proteins are held together to form a proper protein. The following amino acid structural characteristics are, carbons, hydrogen atoms, and carboxyl groups. Alpha Carbon is a necessity to hydrogen atoms, carboxyl groups, and the amino groups in protein structures. The secondary structure causes the structure to fold, curve, and make loops, that gives the protein its' dimentinal shape. The two types of secondary structures are alpha helix structures and beta pleated sheet. The alpha helix structure looks like a coil and is bonded by multiple hydrogens. The beta pleated sheet is folded and held together by hydrogen bonds in between polypeptide units. The third level, the tertiary structure is a broad dementinal structure that has several types of bonds and forces to keep the protein in tact. The shaping of a protein is caused by the hydrophobic interactions. Amino acids and hydrophilic will make a great amount of contact with their

The actin-myosin interaction is most commonly known for its role in sliding filament theory, where myosin II bundles interact with actin filaments to shorten muscle sarcomeres and ultimately contract the muscle. However the myosin superfamily is huge, numbering 17 different proteins to date, and encompassing many different roles. The interaction of myosin and actin in non-muscle cells is thus a huge topic, but in understanding the structure, function and regulation of this part of the cytoskeleton, it is possible to find new drug targets and design new treatments to a huge number of diseases. One such target is the Rho-associated protein kinases (ROCKs), which are responsible for the regulation of the actin myosin cytoskeleton. This report aims to briefly cover the basic role of the actin-myosin cytoskeleton in non-muscle cells, how it is regulated by the ROCK family of serine/threonine kinases, and how ROCK inhibitors have could have huge therapeutic potential.

Unlike many other cells, muscle cells only appear strung together in fibers. The nucleus or nuclei of a fiber is pushed up against the edge of the membrane to make room for myofibrils within the cell. Myofibrils within the cell are part of the cytoskeleton and contain filaments of actin and myosin that work to move the muscle. These myofibrils have repeating patterns that appear as bands on muscle fibers. Each of these repeating sections is known as a sarcomere. These fibers cause the overall shape of the myocyte to be long and tubular. (Liner, 2017)

Proteins are arguably the most structurally and functionally complex structures known to man. Through evolution spanning billions of years, these macromolecules have been perfected to perform many functions necessary for life. Proteins contain four distinct levels of structure and are composed of simple organic compounds known as amino acids. (Alberts, Bruce et al 2000) Amino acids are joined together by peptide bonds made during protein biosynthesis, and the linked amino acid chain is known as a polypeptide chain. DNA determines the amino acid sequence and the sequence is what determines the primary level of protein structure. This level of structure determines the protein’s shape, which affects the assembly and function of