Protein carbon group

When both building block units are m place on the acyl carrier protein carbon-carbon bond formation occurs between the a carbon atom of the malonyl group and the carbonyl carbon of the acetyl group This is shown m step 1 of Figure 26 3 Carbon-carbon bond formation is accompanied by decarboxylation and produces a four carbon acetoacetyl (3 oxobutanoyl) group bound to acyl earner protein... 

One way in which to probe the structural surroundings of a protein is to monitor the pH behavior of specific carbon sites of the C probes. pH-titration studies, of given resonances, had previously been used for probing of the protein structure, because they are known to provide information concerning electrostatic (salt-bridging) interactions in the protein, neighboring group-ionizations, and local environments. ... 

Under certain conditions, such as conformational restrictions or absence of any better acceptors, carbon-bound fluorine presumably accepts hydrogen bonds from protein functional groups (Section 2.2.1). 

A third lipid anchor is provided by the polyprenyl farnesyl (15-carbon) and geranylgeranyl (20-carbon) groups in thioether linkage to cysteine residues. These must be present in specific recognition sequences at the C termini of proteins, most often with the sequence CAAX.211-215 The prenylation (also called isoprenyla-tion) reaction is followed by proteolytic removal of the last three residues (AAX) and methylation of the new C-terminal carboxyl group as is discussed in Chapter 11, Section D,3. See also Chapter 22, Section A,4. 

The nutritional consequences of an excess protein diet are the same as those of an excess carbohydrate or excess fat diet lipid biosynthesis and fat deposition. Additionally, the protein amino groups must be detoxified and eliminated. The nutritional consequences of a diet lacking complete protein—that is, one that doesn t supply the essential amino acids in the proportions needed for synthesis of proteins and neurotransmitters—also include excess ammonia generation. In this case, muscle proteins are degraded to supply enough of the limiting essential amino acid. The other amino acids are broken down, with the carbon chains metabolized into carbohydrates (and, potentially lipid). The leftover amino groups must then be eliminated as urea. 

This acid is closely related to the preceding one. It is hydroxy-phenyl alanine, the group (—C6H4OH) being substituted in the beta carbon group of alanine. Tyrosine is of especial interest as it was one of the first amino acids to be obtained from proteins. It can be easily obtained from cheese. 

For efficient transport of relatively insoluble CO2 from the tissues where it is formed to the lungs where it must be exhaled, the buffers of the blood convert CO2 to the very soluble anionic form HCOJ (bicarbonate ion). The principal buffers in blood are bicarbonate-carbonic acid in plasma, hemoglobin in red blood cells, and protein functional groups in both. The normal balance between rates of elimination and production of CO2 yields a steady-state concentration CO2 in the body fluids and a relatively constant pH. 

Iron-sulfur proteins, Fe-S-proteins a group of proteins found in all organisms. They contain iron-sulfur centers (iron-sulfur clusters) and take part in electron transfer processes. They are involved In Hj metabolism, nitrogen and carbon dioxide fixation, oxidative and photosynthetic phosphorylation, mitochondrial hydroxylation and nitrite and sulfite reduction. The iron in the active centers is coordinated with the sulfur atoms of cysteine residues. In addition, all Fe-S-proteins except for Rubredoxins (see) contain the same number of labile or inorganic sulfur atoms as iron atoms, and both are covalently bound in iron-sulfur clusters. Since the iron is not bound in a porphyrin ring, this group of proteins is included in the Non-... 

Carbon disulfide, carbonyl sulfide, and the singlet form of atomic sulfur are electrophilic and should readily react with nucleophiles. The nucleophilic attack by protein amino groups on the electron-deficient carbon of carbon disulfide to yield a dithiocarbamate that cyclizes into a thiazolidone has been known for some time (e.g., Cohen et (Figure 8). It would seem unlikely that the... 

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