Major biochemical

FIGURE 11.16 Phosphoryl and pyrophosphoryl group transfer, the major biochemical reactions of nncleoddes. 

Muscle is the major biochemical transducer (machine) that converts potential (chemical) energy into kinetic (mechanical) energy. Muscle, the largest single tissue in the human body, makes up somewhat less than 25% of body mass at birth, more than 40% in the young adult, and somewhat less than 30% in the aged adult. We... 

The major biochemical events occurring during one cycle of muscle contraction and relaxation can be represented in the five steps shown in Figure 49-6 ... 

The major biochemical features of neutrophils are summarized in Table 52-8. Prominent feamres are active aerobic glycolysis, active pentose phosphate pathway, moderately active oxidative phosphorylation (because mitochondria are relatively sparse), and a high content of lysosomal enzymes. Many of the enzymes listed in Table 52-4 are also of importance in the oxidative metabolism of neutrophils (see below). Table 52-9 summarizes the functions of some proteins that are relatively unique to neutrophils. 

Table 52-8. Summary of major biochemical features of neutrophils.

Phosphate condensation reactions play an essential role in metabolism. Recall from Section 14.6 that the conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) requires an input of free energy ADP -I-H3 PO4 ATP +H2O AG° — +30.6kJ As also described in that section, ATP serves as a major biochemical energy source, releasing energy in the reverse, hydrolysis, reaction. The ease of interchanging O—H and O—P bonds probably accounts for the fact that nature chose a phosphate condensation/hydrolysis reaction for energy storage and transport. 

The binding of calcium ion to calmodulin, a major biochemical regulator of ion pumps and receptors, occurs on a time scale about a thousand times shorter than that observed for RNA conformational change. This Ca2+-calmodulin binding, which can be followed successfully by nuclear magnetic resonance (NMR), occurs in about ten milliseconds. 

Five of the major biochemical effects of the hormone illustrate the processes that are modified by insulin. 

The tightly regulated pathway specifying aromatic amino acid biosynthesis within the plastid compartment implies maintenance of an amino acid pool to mediate regulation. Thus, we have concluded that loss to the cytoplasm of aromatic amino acids synthesized in the chloroplast compartment is unlikely (13). Yet a source of aromatic amino acids is needed in the cytosol to support protein synthesis. Furthermore, since the enzyme systems of the general phenylpropanoid pathway and its specialized branches of secondary metabolism are located in the cytosol (17), aromatic amino acids (especially L-phenylalanine) are also required in the cytosol as initial substrates for secondary metabolism. The simplest possibility would be that a second, complete pathway of aromatic amino acid biosynthesis exists in the cytosol. Ample precedent has been established for duplicate, major biochemical pathways (glycolysis and oxidative pentose phosphate cycle) of higher plants that are separated from one another in the plastid and cytosolic compartments (18). Evidence to support the hypothesis for a cytosolic pathway (1,13) and the various approaches underway to prove or disprove the dual-pathway hypothesis are summarized in this paper. 

Thus primary cells (i.e., obtained freshly from a human or animal organ) may show poor viability in medium- to long-term experiments, and this can limit their usefulness to short-term exposures. There are also major biochemical changes, which occur with time in primary cells,... 

The major biochemical changes observed are a striking depletion of ATP, impaired protein synthesis, defective incorporation of amino acids, and the appearance of RNA and proteins containing the ethyl rather than the methyl group. The plasma levels of triglycerides, cholesterol, lipoprotein, and phospholipid are all decreased. 

Lead causes damage to a variety of organs and also causes significant biochemical effects. Thus, the kidneys, testes, bones, gastrointestinal tract, and the nervous system are all damaged by lead. The major biochemical effect is interference with heme synthesis giving rise to anemia. 

The simple string of letters denoting the amino acid sequence of a given protein belies the wealth of information this sequence holds. As more protein sequences have become available, the development of more powerful methods for extracting information from them has become a major biochemical enterprise. Each protein s function relies on its three-dimensional structure, which... 

Large metabolic charts have been designed to display all the major biochemical pathways. Such charts present a bewildering array of interconnected pathways, making it difficult to appreciate relationships between different pathways. The overall operational aspects of metabolism may be clarified by simpler block diagrams that omit details and focus on functional relationships. Such a functional block diagram for a typical heterotrophic aerobic cell is shown in figure 11.4. The metabolism of such a system is symbolized by two functional blocks ... 

Besides a difference in the number of phosphate moieties, what are the major biochemical differences between NAD+ and NADP + ... 

McCarthy, M., J. I. Hedges, and R. Benner. 1996. Major biochemical composition of dissolved high molecular weight organic matter in seawater. Marine Chemistry 55 281-298. 

What is the major biochemical effect of lead, and how is this effect manifested ... 

Cowie, G.L., and Hedges, J.I. (1992) The role of anoxia in organic matter preservation in coastal sediments relative stabilities of the major biochemical s under oxic and anoxic depositional conditions. Org. Geochem. 19, 229-234. 

Genotype Major biochemical changes Enzyme affected... 

In this chapter, we will study the major biochemical mechanisms involved in the transformation of insecticides. We will also consider some specific examples of insecticide metabolism in major classes. 

Military support to civil authorities is the final tier in the nation s disaster response system. Federal resources that may be implemented in the event of a major biochemical or radiation disaster are the U.S. Army Special Medical Augmentation Response Teams. The mission of the SMART teams is to provide short-duration medical liaison to local, state, federal, and DOD agencies responding to disasters, civil-military cooperative actions, humanitarian assistance missions, weapons of mass destruction incidents, or chemical, biological, radiological, nuclear, or explosive incidents. There are 37 SMART teams, including two burn SMART teams operated by the U.S. Army Institute of Surgical... 

A major biochemical breakthrough in the biochemical investigation of nitrogenase was the ability to prepare EPR-active inhibitor states of the enzyme. Under traditional... 

Cowie, G. L., J. I. Hedges, F. G. Prahl, and G. J. De Lange. 1995. "Elemental and major biochemical changes across an oxidation front in a relict turbidite An oxygen effect." Geochimica Cosmochimica Acta 59 33-46. 

Cowie, G. L. andj. 1. Hedges. 1995. "Assimilation and alteration of the major biochemicals on ingestion of diatoms by an herbivorous zooplankton." Limnology and Oceanography... 

As discussed above, NMR spectroscopy has alluded to the presence of many major biochemicals (carbohydrates, proteins and lipids) in HMWDOM. To determine which of these biochemicals are important and how each contributes to the observed NMR spectrum several investigators have performed molecular level analyses of HMWDOM. The discussion below wiU focus primarily on proteins and related compounds. 

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