Function Of Myoglobin Research Articles

An application of vector space search methods to the Patterson function of myoglobin

By searching the 1.5 Å Patterson function of myoglobin (space group P21) with intragroup vector sets characteristic of the heme group and of the main chain of a 4- or 5-turn α-helix, it is shown that it is possible to determine the orientation of the heme, and the axial directions of the prominent helices A, B, E, G, and H. Additional searches performed with helices A, G, and H correctly reveal the true orientations about the helical axes. Translation searches with intergroup vectors, similarly yield the correct positions of the heme and helices A, G, and H relative to a 21 axis. The relative y coordinates (along 21) of the heme group and a helix can be unambiguously found by a search using vectors from the heme Fe atoms to the correctly oriented helix. Several image-seeking functions are explored by varying the selection and weighting of the search vectors. The best results are obtained with an image-seeking function defined as a weighted average over a selected subset of search vectors. The selection is made for each setting of the vector set, and is based on the value of the Patterson function at each search vector in relation to the distribution of values in the entire Patterson function.

A study of the concentration and function of mammalian and avian myoglobin in type I skeletal muscle fibres

1. 1. The concentration of myoglobin in type I fibres of the rat and pigeon has been estimated from known biochemical data using histochemical and morphometric techniques. 2. 2. The concentration of myoglobin in rat type I fibres (6·9 mg/g muscle wet wt.) is considerably greater than simple biochemical assay would indicate. 3. 3. Oxymyoglobin in pigeon type I fibres is incapable of acting as an oxygen store for longer than 120 msec.

Coboglobins: cobalt substitution and the nature of the prosthetic group--apoprotein interaction in hemoglobin and myoglobin.

Despite great interest in the structure and function of hemoglobin and myoglobin, many molecular processes involved in reversible oxygen binding are unexplained. In particular, we wish to know how the apoprotein and prosthetic group interact to give the properties associated with the holoprotein: Prosthetic Group

The oxygen equilibrium of yeast hemoglobin

Oxygen transport is considered to be the most important function of hemoglobin and myoglobin. Facilitated transport of oxygen may be an important function of myoglobin, and it has been suggested that the hemoglobin of microorganisms functions similarly [l] . Many reports concerning non-circulating hemo globin have appeared in the literature [2-l l] . Keilin originally discovered a hemoglobin-like pigment in yeast [2], but reported that over a period of 4 yr he had detected hemoglobin in bakers yeast only twice [2]. Because hemoglobin so seldom appears in yeast celIs it has been difficult to make any extensive study of the properties of this hemoprotein. During our generalsurvey of the hemoproteins in yeast, we have identified some species of C~ndidu which consistently have a high hemoglobin content. We have subsequently succeeded in purifying this hemoglobin [ 121. In this communication we will present measurements of the oxygen affinity of this hemoglobin as obtained using a sensitive bioluminescent oxygen indicator. The data provides evidence that the yeast hemoglobin binds oxygen non-cooperatively with high affinity and appears to be a “primitive” form of the hemoglobin of higher organisms, Moreover, the data indicates that yeast hemogiobin does not significantly enhance the diffusion of oxygen to the cytrochrome oxidase of the cells in which it is present.

Myoglobin-facilitated oxygen diffusion: role of myoglobin in oxygen entry into muscle.

Myoglobin-facilitated oxygen diffusion: role of myoglobin in oxygen entry into muscle.

Histochemical Demonstration of Myoglobin in Skeletal Muscle Fibres and Muscle Spindles

MOST muscles are composed of a mixture of two types of muscle fibre which can be shown to differ in myoglobin content. Slow type 1 fibres are narrow, contain numerous mitochondria and are poor in glycogen and phosphorylase. Fast type 11 fibres are broad, contain few mitochondria and are rich in glycogen and phosphorylase1. It has been assumed that type 1 fibres are rich in myoglobin and these are termed red. Type 11 fibres are assumed to be poor in myoglobin and are termed white. Similarly, it has been assumed that the large nuclear bag fibres of muscle spindles are poor in myoglobin and that they contract rapidly. The smaller nuclear chain fibres would be expected to be rich in myoglobin and contract slowly. No comprehensive survey of the myoglobin content of muscle fibres has previously been reported. Knowledge of the precise distribution of myoglobin in extrafusal and intrafusal fibres would throw light on the function of myoglobin and muscle spindle activity.

British Biophysical Society Symposium on “Structure, Function and Biosynthesis of Haemoglobin and Myoglobin”

British Biophysical Society Symposium on “Structure, Function and Biosynthesis of Haemoglobin and Myoglobin”

Hemoglobin and Myoglobin

Publisher Summary This chapter describes hemoglobin and myoglobin. Hemoglobin and myoglobin are, among all proteins, ones that have been, and are, most actively studied; an enormous number of papers have been published over the past hundred years on all aspects of their properties and behavior. The study of these proteins has gone beyond the interest in their physiological role as oxygen carriers because they represent ideal models for investigating the properties of proteins in general, especially of enzymes. Correspondingly, current knowledge of the structure and function of hemoglobin and myoglobin is far greater than that available for any other protein. In spite of this, however, many questions still remain unsolved regarding the exact molecular mechanisms involved in the function of these proteins. Before discussing the properties of respiratory heme proteins, it is necessary to briefly describe some properties and reactions of their prosthetic group, mainly because the characteristic physiological functions of these proteins arise from the intrinsic reactivity of the heme.

FACILITATED DIFFUSION OF OXYGEN THROUGH HAEMERYTHRIN SOLUTIONS.

HAEMOGLOBIN present in water solution facilitates the steady-state diffusion of oxygen through that solution1,2; the total oxygen flux is greater than the flux through an equivalent protein solution, for example, a solution of methaemoglobin. The haemoglobin-mediated oxygen flux may be considered to be additive to the simple diffusion flux of oxygen. Fig. 1, which although obtained with the protein haemerythrin is entirely typical of results obtained with haemoglobin, reveals that the flux mediated by an oxygen-binding protein is constant in amount for a particular protein concentration and independent of the oxygen partial pressure difference across the solution at oxygen partial pressures sufficient to saturate largely the carrier. This property has the interesting consequence that at the low oxygen partial pressure presumably existing in tissue the haemoglobin mediated flux would be expected to make up the largest part of the total oxygen flux. Quite possibly the facilitation of oxygen diffusion in the interior of muscle cells is a major function of myoglobin.