methylidyne SeeCARBYNE.
me-too drug A compound that is structurally very
similar to already known DRUGs, with only minor
pharmacological differences.
Meyerhof, Otto Fritz (1884–1951) GermanPhysiol-
ogist, chemist Otto Fritz Meyerhof was born on April
12, 1884, in Hannover to Felix Meyerhof, a merchant,
and Bettina May. He went to the Wilhelms Gymnasium
(classical secondary school) in Berlin, leaving at age 14
only to have kidney problems two years later that kept
him confined for a long period. He eventually studied
medicine at Freiburg, Berlin, Strassburg, and Heidelberg
and graduated in 1909. From 1912 he worked at the
University of Kiel, becoming a professor in 1918.
Meyerhof conducted experiments on the energy
changes in cellular respiration. For his discovery of the
fixed relationship between the consumption of oxygen
and the metabolism of lactic acid in the muscle, he was
awarded, together with the English physiologist A.V.
Hill, the Nobel Prize for physiology or medicine in
- In 1925 Meyerhof successfully extracted the
enzymes that convert glycogen to lactic acid from the
muscle. He introduced the term glycolysisto describe
the anaerobic degradation of glycogen to lactic acid,
and he showed the cyclic nature of energy transforma-
tions in living cells. This metabolic pathway of glycoly-
sis—conversion of glucose to lactic acid—is now
known as the Embden-Meyerhof pathway after Meyer-
hof and Gustav George Embden.
During World War II, he went to the United States
and became a research professor of physiological chem-
istry, a position created for him by the University of
Pennsylvania and the Rockefeller Foundation. He died
from a heart attack on October 6, 1951.
mica A group of silicate minerals composed of vary-
ing amounts of aluminum, potassium, magnesium,
iron, and water that forms flat, platelike crystals that
cleave into smooth flakes.
micellar catalysis The acceleration of a CHEMICAL
REACTIONin solution by the addition of a surfactant at
a concentration higher than its CRITICAL MICELLE CON-
CENTRATIONso that the reaction can proceed in the
environment of surfactant aggregates (MICELLEs). (Rate
enhancements may be due, for example, to higher con-
centration of the reactants in that environment, more
favorable orientation and solvation of the species, or
enhanced rate constants in the micellar pseudophase of
the surfactant aggregate.) Micelle formation can also
lead to a decreased reaction rate.
See alsoCATALYST.micelle Surfactants in solution are often association
COLLOIDs, i.e., they tend to form aggregates of colloidal
dimensions that exist in equilibrium with the molecules
or ions from which they are formed. Such aggregates
are termed micelles.
See alsoINVERTED MICELLE.Michaelis-Menten kinetics The dependence of an
initial RATE OF REACTIONupon the concentration of a
SUBSTRATES that is present in large excess over the con-
centration of an enzyme or other CATALYST(or reagent)
E, with the appearance of saturation behavior follow-
ing the Michaelis-Menten equation:
nu = V[S]/(Km+ [S]),
where nu is the observed initial rate, Vis its limiting
value at substrate saturation (i.e., [S] >> Km), and Kmis
the substrate concentration when nu = V/2. The defini-
tion is experimental, i.e., it applies to any reaction that
follows an equation of this general form. The symbols
Vmaor numaare sometimes used for V.
The parameters Vand Km(the Michaelis constant)
of the equation can be evaluated from the slope and
intercept of a linear plot of nu–1 against [S]–1 (a
LINEWEAVER-BURK PLOT) or from the slope and inter-
cept of a linear plot of nu against h/[S] (Eadie-Hofstee
plot).
A Michaelis-Menten equation is also applicable to
the condition where E is present in large excess, in
which case the concentration [E] appears in the equa-
tion instead of [S]. The term has sometimes been used
to describe reactions that proceed according to the
schemeE + S kk^1 ES kcat Products +- 1
⇀↽ → EE178 methylidyne