Physiological properties

A very few fluorine-containing substances are, on the other hand, extremely toxic. The most (in)famous of these are fluoroacetic acid (ID50 4.7 mg kg in rats, IDioo 5 mg kg in humans [33] - the doses after which 50% or 100%, respectively, of the tested individuals die) and perfluoroisobutene (IC50 1 ppm - the concentration in ambient air for 4 h after which half of the tested individuals die). 

Fluoroacetic acid has been identifled as the toxic component of the South African plant gijblaar (Dichapetalum cymosum) [34]. Its mechanism of action is based on inhibition of the citric acid cycle, the main source of metabolic energy in all animals [35]. In this cyde, fluoroacetate can replace acetate as a substrate of aconi-tase, an enzyme complex which usually forms dtrate by addition of acetate to a-oxoglutarate. The resulting fluorocitrate is binds tightly to the enzyme, but cannot be further converted to ds-aconitate and isocitrate [36], thus inhibiting aconitase. 

It must also be remembered that some fluoroorganic compounds are, if ingested, degraded to toxic metabolites. This phenomenon occurs with w-fluoro fatty adds, aldehydes, alcohols, amines, and related compounds - because of metabolic oxidation of fatty acids by step-wise cleavage of C2 units, w-fluoro fatty acids with an even number of carbon atoms end up as toxic fluoroacetate (e. g. 

Some widely used fluorotensides have recently become the focus of environmental concerns. Compounds such as perfluorooctyl sulfonic acid and perfluoroocta-noic acid (PFOA) have environmental lifetimes on a nearly geological time-scale. Traces of these substances have been found to be present in the remotest locations on earth and the source of the contamination remains unclear. There is not yet much unambiguous evidence of negative physiological effects of these widely used fluorosurfactants, although perfluorooctyl carboxylates have attracted some critical attention as a potential developmental toxin in rats [37]. Some major producers have, therefore, already started to replace these tensides by more readily degradable alternative compounds. 

Characteristics of C-F Systems, in Organofiuorine Chemistry Principles and Commercial Applications, R. E. Banks, B. E. Smart, J. C. Tatlow, eds.. Plenum Press, New York, 1994, pp. 57-88. 

At room conditions, hydrogen sulfide is a colorless gas that has a highly offensive odor. It has a density of about 1.33 kg/m3, which is slightly larger than air. Thus it tends to accumulate in such low areas as ditches and the bottom of vessels. 

Hydrogen sulfide has a characteristic rotten egg smell. The human olfactory is capable of detecting the presence of only a few parts per million (ppm) in the air, although some individuals can detect less than 1 ppm. Most humans can detect H2S at levels much less than 10 ppm. 

The primary route of exposure to H2S is inhalation. Hydrogen sulfide is classified as a chemical asphyxiant. A single breath of HjS at a concentration of 1000 ppm is sufficient to kill an individual. Prolonged exposure at 250 ppm levels can cause pulmonary edema (the lungs filling with fluid), which can lead to death. However, even at low concentrations (less than 10 ppm), H2S may cause irritation of the eye and respiratoiy system (including the nose, mouth, and bronchial tubes). The effect of hydrogen sulfide can be exacerbated if the individual already suffers from such a pulmonaiy disease as asthma. 

Although H2S has a strong offensive odor, this should not be used as a guide to expose to this toxin. The olfactoiy quickly deadens to the smell of H2S, making smell a somewhat unreliable test for exposure. 

Hydrogen sulfide can also affect the eyes of an individual exposed to this toxin. Exposure to only 20 to 50 ppm for one hour may cause damage to the eye. Thus exposure to the eyes is to be avoided. 

Rijkens, F., Organogermanium Compounds, Chapters Biological Activity of Germanium Compounds in Organogermanium Compounds, Org. Chem. Inst. TNO, Utrecht, Neth., 1960, pp. 46/9. 

Caujolle, F., Caujolle, D., Bouissou, H., Pharmacodynamic Toxicite des germanes aliphatiques pour le rat, Compt. Rend. 257 [1963] 551/2. 

Rijkens, F., Van der Kerk, G. J. M., The Biological Activity of Organogermanium Compounds, in Investigations in the Field of Organogermanium Chemistry, Utrecht, 1964, pp. 95/115. 

Cremer, J. E., Aldridge, W. N., Toxicological and Biochemical Studies on Some Trialkylgermanium Compounds, Brit. J. Ind. Med. 21 [1964] 214/7. 

Pure ocytocin is soluble in slightly hydrated methyl and ethyl alcohols, and in butanols. The partition coefficients between these solvents and 

Butyl alcohols solubilize the ocytocic substances only from extracts treated with acids at a pH close to 3.9, at which pH proteins precipitate. The same phenomenon is true of hog pituitary. This behavior is due to the ocytocin-protein-complex which may represent the mother molecule of Van Dyke. 

Precipitating reactants for basic amino acids such as picric and picrolonic acids do not precipitate bovine ocytocin, but picric acid precipitates hog ocytocin (400). 

The isoelectric point of the peptide isolated from cow is pH 8.5. This property is a basis for a method of electrophoretic purification (309). 

The fact that tyrosine of the peptide reacts with diazomethane to give 0-methyltyrosine (594) seems to indicate that the phenolic group of tyrosine is free. 

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Recently, new esters possessing physiological properties have been synthesized (67). 

The physical properties of commercial alkoxysilanes are provided in Table 1. Two classes of silane esters have very distinct properties and are generally considered apart from alkoxysilanes. Sdatranes are compounds derived from trialkanolamines and have siHcon—nitrogen coordination. These are generally hydrolytically stable and have unique physiological properties (3). A second special class of monomeric esters are cycHc diesters of polyethyleneoxide glycols designated sila-crowns, which have appHcation as catalysts (4). Neither silatranes nor sila-crowns are considered herein. 

H-Pyrido[3,2-c]azepine, 7-methoxy-nucleophilic displacement reactions, 7, 514 Pyridoazepines synthesis, 7, 535, 540 Pyridoazepinones synthesis, 7, 531 Py rido[2,1-a]benzazepin-6-one physiological properties, 7, 546 Py rido[ 1,2-a]benzimidazoles reactions, 6, 1041... 

This, on reduction with zinc dust and acetic acid, yielded the corresponding oxime, which was further reduced by sodium amalgam to -3 4 5-trimethoxyphenylethylamine, CgHjj(OMe)3. CH. CH. NHg, and this proved to be identical with mezcaline (I). Like the latter, it behaves on analysis as if it contained the grouping —NHMe but this had already been disproved by Heffter. Interest in the remarkable physiological properties attributed to mezcaline has led to many syntheses of this alkaloid and of its isomerides and analogues. ... 

On the other hand, because enantiomers differ in their three-dimensional structure, they often interact with biochemical molecules in different ways. As a result, they may show quite different physiological properties. Consider, for example, amphetamine, often used illicitly as an upper or pep pill. Amphetamine consists of two enantiomers ... 

The physiological properties of selenium compounds are similar to those of arsenic compounds. Any selenium dioxide solid or solution spilled on the skin should be removed immediately by washing under running water. 

Nonmuscle/smooth muscle myosins-Il are structurally similar to striated muscle myosin-II, but they have slower rates of ATP hydrolysis than do their striated muscle counterparts. Nonmuscle/smooth muscle myosin-II is also regulated differently than striated muscle myosin-II. Nonmuscle myosin-II is divided into the invertebrate and vertebrate branches (Cheney et al., 1993). This group is ubiquitous because it is present in most lower organisms, such as slime molds, amoeba, sea urchins, etc., and in virtually all mammalian nonmuscle cells. Smooth muscle myosin-II is also somewhat heterogeneous in that at least three separate forms of smooth muscle heavy chains, with molecular weights of 196,000, 200,000, and 204,000 have been identified (Kawamoto and Adelstein, 1987). The physiological properties of these separate myosin heavy chains are not yet known. 

The recent explosion in the discovery of new myosin genes has led to the idea that myosins from different classes probably co-exist in cells. This has raised the obvious question as to what functions these myosins subserve within cells. Up to now, only the genes have been cloned for many of the 35 unique myosins. But this is not a question that can be answered solely by cloning rather, it is absolutely imperative to biochemically characterize these proteins if we are to understand their physiological properties. One way to do this is to express the entire protein or parts of the proteins in bacteria, yeast, or insect cells, and to then purify and characterize... 

R = Et) possessing a diverse range of physiological properties were prepared in a chemoenzymatic strategy using the fungi B. bassiana and Beauveria caledonica [207]. 

Alibert, G., Bondet, A.M., Canut, H. Rataboul, P. (1985). Protoplasts in studies of vacuolar storage compounds. In The Physiological Properties of Plant Protoplasts, ed. P.E. Pilte, pp. 105-15. Berlin Springer. 

Physical and Physiologic Properties of Fatty Acids Reflect Chain Length and Degree of Unsaturation... 

Figure 38-4. Examples of three types of missense mutations resulting in abnormal hemoglobin chains. The amino acid alterations and possible alterations in the respective codons are indicated. The hemoglobin Hikari p-chain mutation has apparently normal physiologic properties but is electrophoretically altered. Hemoglobin S has a p-chain mutation and partial function hemoglobin S binds oxygen but precipitates when deoxygenated. Hemoglobin M Boston, an a-chain mutation, permits the oxidation of the heme ferrous iron to the ferric state and so will not bind oxygen at all.

Cyclic GMP is made from GTP by the enzyme gua-nylyl cyclase, which exists in soluble and membrane-bound forms. Each of these isozymes has unique physiologic properties. The atriopeptins, a family of peptides produced in cardiac atrial tissues, cause natriuresis, diuresis, vasodilation, and inhibition of aldosterone secretion. These peptides (eg, atrial natriuretic factor) bind to and activate the membrane-bound form of guanylyl cyclase. This results in an increase of cGMP by as much as 50-fold in some cases, and this is thought to mediate the effects mentioned above. Other evidence links cGMP to vasodilation. A series of compounds, including nitroprusside, nitroglycerin, nitric oxide, sodium nitrite, and sodium azide, all cause smooth muscle re-... 

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