The name is absent

there are about ten of the I_i and at least seven each of the O_i and R_l, all
with formidable organic chemical names. In the case of the electron
transport scheme, there is enough variation among species to justify the
flexibility. Finally, we want to be able to recover when somebody
discovers a new step in the chain, which is not unlikely.

We are not in a position to derive kinetic relations until we write down
the fundamental steps of the individual stoichiometric equations. This
information is not known definitely for any of the reactions involved, and
can only be guessed at for some. The following is an attempt at such
guesswork; Figure 3 shows a possible mechanism for one of the electron

E _i ≈ THE SPECIFIC ENZYME FOR STEP i
Aj = ANY CHEMICAL SPECIES PRESENT

∕A∖

(I) Ej +Aj =^(e)ij (MODIFIED CATALYST)

<2) O_i * φ_ii = (Og)_iii or           —(ε)iji÷ι

(ʒ) R_itlφg)_iji = (gθ)_ijifltR _or O_i +(∣R)_iji^(R^_ji÷O_i+∣

«>      (εθ)_4ift=(g),∣ ⁺θ∣÷_l °’ (Rε)_u∣ =≠ (e)₁₁+R_i

net: O_i + R_if∣ = O_ifl ÷R_i O_i ÷R_i+l O_itl + R_i

FIG. ʒ - HYPOTHETICAL DETAILED MECHANISM OF ONE STEP

IN THE ELECTRON TRANSPORT PATHWAY

transport steps. Briefly, ( 1) states that the enzyme for step i can “react,”
(adsorb on its large and complex surface) various species A_i: this is the
allosteric mechanism, and generalizes the function of a catalyst signifi-
cantly. The modified form ɛ may be either more or less active as a
catalyst than E_i, so that the concentration of A_j may retard or enhance
the rate of the reaction although it has nothing to do with the stoichiom-
etry. (2) through (4) are the possible steps for the accomplishment of
the overall purpose. A similar mechanism can be implied for any one of
the steps in the Krebs cycle.

An analogous mechanism for the electron transport steps which include
ATP formation is shown in Figure 4. More complicated schemes can
easily be constructed. Any mechanism which is less complicated, in that
it allows the redox step without ATP formation, would have to be
rejected. Oxygen utilization apparently does not proceed without
phosphate fixation.

The Kinetics of the Example Set

It might be well to state an objective before proceeding with the

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