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DK: a symbol used in this volume to represent the diffusion coefficient of
K+.
decapiperidinum ion: a long-chain organic cation.
decapyrrolinium ion: a long-chain organic cation.
D-effect: direct electrostatic effect mediated through space.
D-fucose: the D-isomer of one of the hexoses; also known as 6-desoxygalactose.
D-galactose: a hexose, one of the few sugars other than D-glucose, which are found in animals (In combination with D-glucose, it forms lactose in mammalian milk.)
D-glucose: the D-isomer of the hexose also known as dextrose or grape sugar. It is the main energy source of many living organisms including humans.
D-sorbitol: See sorbitol.
D-xylose: a naturally occurring pentose, often isolated from agricultural wastes (e.g., corn cobs). As a rule, not metabolized by animals or yeasts.
Danielli-Harvey paucimolecular theory: a theory proposed in 1939 by E. N. Harvey and J. Danielli for the chemico-physical make-up of the cell membrane, in which a core of lipid bilayers are covered on both side by layers of globular proteins.
DC electric field: direct current electric field.
dead state, death state: the counterpart of the concept of the living state introduced in the AI Hypothesis The dead state or death state is the state of the cell or protoplasm when it has reached a low (negative) energy and high entropy state but unable to revert back to the high (negative) energy-low entropy living state.
de Boer-Zwikker polarization theory: See polarization theory.
Debye dielectric reorientation time, (Debye dielectric relaxation time),
(τD): the rate constant for the decay of the macroscopic polarization when the applied field is abruptly removed.
debye: unit of electric polarizability equal to 1024
cm3, named after Peter J. W. Debye, Dutch-born American physicist (1884-1966).
Debye-Hückel theory of dilute ionic
solution: a theory of dilute ionic solution proposed by P. Debye and W.
Hückel in 1923, in which ions of one electric charge in a dilute solution are surrounded by a cloud of oppositely charged ions In this theory there is no, or little close-contact association of oppositely charged ion pairs.
de facto multiatomic ion: By itself a Na+ comprises a single atom. However, being surrounded by a more or less permanent shell of water molecules (of
hydration), Na+ is in reality or de facto multiatomic.
denature, denaturation: See denatured protein.
denatured proteins: In 1931 H. Wu offered the first definition of protein denaturation thusly:
"denaturation is a change in the natural protein molecules whereby it become insoluble in solvents in which is was previously
soluble."107 p 37 n4 Since then, the meanings of native and denatured protein have changed a great deal and the word "native" is used often to designate the crystal-line folded form of a (globular) protein. In this context, denaturation refers to the change from the folded introvert conformation to the fully-extended extrovert conformation. Since there are extensive evidence now that major proteins in their genuinely
native environment inside living cells exist not in the so-called native (introvert) conformation but in the extrovert fully-extended conformation [16.6(1.3)], the word denaturation has not only lost its original intended meaning, it has actually acquired willy-nilly the inverted meaning.
deoxygenated state: The protein hemoglobin can exist in two states. In one state, the heme sites are occupied by oxygen molecules; in the other they are not occupied by oxygen. The state without oxygen on its heme sites is called the deoxygenated state.
deoxyribonucleic acid, (DNA): a nucleic acid especially abundant in the nuclei of animal and plant cells Upon hydrolysis it yields adenine, guanine, cytosine, thymine, phosphoric acid and deoxyribose.
depolarization: causing to become wholly or partially unpolarized.
dialysis: the separation of substances on the basis of their different rates of diffusion through selectively permeable membranes, especially the separation of proteins from crystalloids.
dichloroacetic acid: Cl2HCOOH, a derivative of acetic acid, in which two of its methyl hydrogen atoms have been replaced by chlorine atoms.
dielectric: a nonconductor of direct electric current.
dielectric constant: also known as specific induction capacity represented as
ξ, it is defined by the equation: F = QQ'/(ξ r2), where F is the force of attraction between two charges Q and Q' separated by a distance of r in a uniform medium with a dielectric constant
ξ.
dielectric saturation: In the intense field near an ion, particles of the polar solvent become strongly oriented so that the effective dielectric constant can no longer have the value usually given but is greatly reduced. This phenomenon is known as dielectric saturation.
differentiation: the act or process of becoming different.
diffusion: a process, which leads to the equalization of concentration in a single phase Diffusion of particles in liquids, gases or solids results from their spontaneous movement caused by thermal agitation.
diffusion barrier: a barrier, which prevents or slows down the equalization of concentration in two contiguous spaces.
diffusion coefficient: the weight of material passing in unit time across a plane of 1 sq. cm. when the concentration gradient is unity Diffusion coefficient measures the rate of diffusion; its magnitude can often tell us about the environment of the diffusing substance.
diffusion equilibrium: A diffusing substance has reached diffusion equilibrium when the amount of the substance entering any region in the space where diffusion occurs equals the amount of the substance leaving that region.
diffusion head: The word, head, means the difference in elevation of two points in a body of fluid and the resulting pressure of this fluid at the lower point expressible as the height. Diffusion head denotes a similar head in molecular diffusion of a substance dissolved in a fluid rather than
en masse movement of a fluid.
dimerization: the formation of a compound from two similar molecules or entities.
2,4-dinitrophenol: a highly toxic derivative of phenol with two nitro groups introduced respectively at the 2 (ortho) and 4 (para) positions It is a powerful inhibitor
of oxidative phosphorylation, a key step in energy metabolism.
2,3-diphosphoglycerate (2,3-DPG; DPG): a diphosphate ester of glycerol It is an intermediate in glycolysis of animal tissues; found in significant concentration in erythrocytes.
dipole: a pair of equal and opposite electric charges or magnetic poles of opposite sign separated by a small distance.
dipole moment: the product of one of the charges of a dipole unit by the distance separating the two dipolar charges.
direct current: electric current, which does not change its direction with time.
direct inductive effect (D-effect): inductive effect mediated through intervening space.
disaccharide: a sugar that upon hydrolysis produces two monosaccharides Example: sucrose, lactose.
dispersive X-ray microanalysis: A setup, which by combining an electron microscope, an energy-dispersive X-ray detector and a multichannel analyzer, makes possible the analysis of minute quantities of elements in a microscopic specimen.
displacement, D: a vector defined by the relationship: D ≡ E +
4πP, where
E, another vector is the electric field intensity and P, also a vector, is the electrical polarization.
disulfide bond: -S-S-, as in the example of the linkage between two cysteine groups in forming cystine.
DNA: See deoxyribonucleic acid.
(40%) double bond: Two atoms can be joined by a single bond or a double bond. But under certain conditions, the actual bond involves both single and double bond by resonating between the two structures, or one may say, it is a resonance hybrid between the two. An empirical curve relates the distance measured between the two atoms and the amount of single bond, double bond character of a specific bond. Based on this empirical relationship and the actually measured bond length, one may arrive at the conclusion that a specific bond is 40% double bond and 60% single bond.
double reciprocal plot: a way of presenting the experimental data in which one plots the reciprocal of the dependent variable against the reciprocal of the independent variable
A converging double reciprocal plot means that the (straight-line) theoretical plots with different slopes converge toward the same spot on the ordinate. (For examples, see Fig.
12 and Fig.59B.)
doublet adsorption-desorption route: one mode of ion entry into (or exit from) a living cell or model It involves the adsorption of the entrant ion on an oppositely-charged fixed ion, a libration step around the fixed ion and desorption from the fixed ion and entry into (or exit from) the living cell or model.
Dowex-50: a sulfonate type of cation exchange resin marketed by Dow Chemical Co.
drug: a substance intended for use in the diagnosis, cure, mitigation, treatment or prevention of disease.
dynamic: of or relating to activity.
dynamic structure: a structure marked by continual change.
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