The research history of myoglobulin

An overview of myoglobulin

Myoglobulin is myofibril thick filament composition units. Exist in striated muscle and smooth muscle. In the muscle movement plays an important role. Its molecular shape, such as bean sprouts, consists of two heavy chains and multiple light chains. The majority of the two heavy chains are spirally wound into a rod-like configuration to form a bean sprout-like rod; the remainder of the heavy chain, together with the light chain, constitutes the flap of the bean sprouts. After activation, the activity of ATP can break down the ATP enzyme. The molecular weight of about 510,000. In the thick silk, are the head of the molecules toward the ends of thick silk, was linearly aligned association.

Introduction to myoglobulin

Myoglobulin is a major component of muscle protein, accounting for 60% of total protein myofilaments. Molecular weight of about 480,000, is 150 nm long rod-like molecules, one end has two heads. Consisting of two H chains with molecular weights of about 200,000 and four L chains with molecular weights of about 17,000 to 25,000. Proteolytic enzyme treatment can be divided into head (H-enzymatic myoglobulin) and tail (L-enzyme myoglobulin). In 0.6M KCl solution dispersed into monomers, but 0.2M below the KCl solution can form associations, automatically aggregated into 1-2 microns long and A wire similar structure. A filaments were formed in the myofibrils with a length of 1.5 m and a width of 10-15 nm. The head protrudes outwards into a bridge. The direction of the head is expressed as a forceps in the central portion of the filament and extending in the opposite direction, with the result that the bare portion without the head portion can be seen at the central portion of the filament at 300 nm. The head in the A wire on each bend 14.3 nm out of 120 ° and I wire corresponds to a period of 42.9 nm. Myoglobulin with ATPase activity, at low ionic strength, and actin reaction, which led to super-precipitation, and actin can promote ATPase activity. ATPase activity and actin reaction, the performance of the active groups in the head, it can be considered that this part of the decomposition of ATP side, while the head activity, the I wire to pull the central part of A wire. The L-chain of myoglobulin plays an important role in ATPase activity (see myoglobulin L chain). Myoglobulin and actin are thought to be associated with all cellular motility and may also be isolated from the brain, myxomycetes, sea urchin eggs, and the like. Myoglobulin was isolated from A. Szent-Gyrgyi (1942), but the equivalent of what is now known as actomyoglobulin is Kuhn (1859) Extracted, and was named myoglobulin. Myoglobulin ATPase activity was discovered by the Soviet V.A.Engelhardt (1939).

There are non-muscle myoglobulin.

Structure of Myoglobulin

Myoglobulin is an elongated asymmetric molecule, shaped like “Y”, about 160nm. It was observed under electron microscopy that it contained two identical long peptide chains and two pairs of short peptide chains, forming two spherical heads and a long rod-like tail. Myoglobulin molecular weight of about 460kD, long peptide chain molecular weight of about 240kD, weighing chain; short chain called light chain. A pair of light chains of muscle myoglobulin treated with 5,5′-dithiobis (α-nitrobenzoic acid, DTNB) were named as DTNB chains with a molecular weight of about 18kD. The other two light chains were only found in the base (PH 11.4) conditions can be separated, called alkaline light chain, molecular weight of 25kD and 16kD, respectively. The shape and structure of myoglobulin from nonmuscle cells such as myxomycetes are very similar to myoglobulin from muscle cells, but it does not have DTNB chains. Two different pairs of light chains are known as essential light chains and regulatory light chains (Regulatory light chain), the molecular weight of 16kD and 18kD. Yan Longfei equal in 1963 for the first time from the tobacco microtubule bundle separation of actomyoglobulin, proved to have ATPase activity, which is higher plants in actin and myoglobulin in the first evidence [3]. Ma Yongze and Yan Longfei (1989) showed that the myoglobulin was present in the tendrils of the pea leaves, and the molecular weight of the two heavy chains was 165 kD and 17 kD and 15 kD, respectively.

The nature and function of myoglobulin

Nature:

Myoglobulin globulin, do not dissolve in water and dissolved in 0.6mol / ml KCl or NaCl solution. It has enzymatic activity, through the interaction with actin, ATP hydrolysis of the terminal phosphate groups, but also hydrolysis of GTP, CTP, etc., will be converted into chemical energy of mechanical energy, resulting in various forms of movement. Physical and chemical studies have shown that myoglobulin solution after adding ATP, the viscosity and flow birefringence decreased significantly. Later confirmed that this is due to actin and myoglobulin complex decomposition, the formation of two axis relatively small protein molecules caused.

Features:

Myoglobulin, the molecular motor of the cytoskeleton, is a multifunctional protein whose primary function is to provide muscle force for muscle contraction. The sliding filament theory suggests that muscle contraction is the result of the sliding of actin filaments and myoglobulin filaments. In the process of muscle contraction, the length of the thick filaments and the filament itself does not change, when the filaments slide, the myoglobulin head and actin molecules in contact (attachment), rotation (tilting), the final detachment As a result of which the filaments are slid relative to each other.

Myoglobulin is also widespread in non-muscle cells, it is the composition of the cytoskeleton, the cytoplasmic flow, organelle movement, material transport, mitosis.