Some additional remarks on the mechanism of oxidative phosphorylation

Vol. 18, No. 2,1965

BIOCHEMICAL AND BIOPHYSICALRESEARCHCOMMUNICATIONS

SOME

ADDITIONAL

REMARKS

OXIDATIVE

ON THE

Theodore Florida

I.

This

Atlantic

University

Raton,

Florida

2’7, 1964

brief

note

amplifies

oxidative

constitutes

Bieber

of Chemistry

Boca

mitochondrial

OF

PHOSPHORYLATION

Department

Received November

MECHANISM

my

paper

on the mechanism

phosphorylation

a response

(Bieber,

to numerous

queries

1964)

that

were

of

and also directed

to me. A.

Phosphorylation

coupled

rather

than

to two-electron

transfer,

such

a region

of the

transferred sites. The

singly This

multiplicity

in the

suggestion

role

obtains

I now the

one-electron

transfer

cytochromes

appear

porphyrin-bound

partial

short

circuit

structural

features,

permanent

proximity

various

steps

of the

special

case.

Since

system it may

role

in addition conceivably

some

carriers,

respiratory

to be equally the

iron (see

Fig.

it will

suited

as required coupling

for

operation.

it contains

for

just

the

the latter

role,

the proper

(H-Y=Z) depot

paper).

situated

for

timing

a may -ferric

of the above-mentioned

be a

-cupric system, roles

simultaneously. B. photosynthetic

The

light-energized organisms

phosphorylation may

also

295

be due,

occurring in large

two

and

of the

cuprous ferrous

the

These

in close

Cytochrome

a protein-bound

both

(or of

electron

previous are

to the porphyrin-bound perform

the

unsaturation

the

2 of my

be noted,

coupling

Chemically

furnishing

play

the others

requisite

is a

explanation

cytochromes in the

well

providing

chain

a partial

while

of transformers

are

of the transport

find

to phosphorylation.

system

and the

that

in

of the cytochromes.

the may

to occur

electrons

region

along

one-electron

play

likely

where

which

advance

transfer,

character

in the

phenomenon

of regular

the porphyrin

chain

of cytochromes

perplexing

is most

due to the chemical

situation

rather

one other)

respiratory

to one-electron

part,

in to

Vol. 18, No. 2, 1965

the

coupling

so,

the

of one-electron

previously

coupling C.

ATP

electrical

of ATP

may the

hydrolysis of Fig.

ATP

hydrolysis

may

be coupled

of the cycles generated

a variety

If

for

such

to one-electron to two-electron

functions

electron

promotion

2) is apt to be more

to electron

of Fig.

promotion

in the life half

electrons,

promotion common

2.

The

electrical

requires

of two

promotion

1 or Fig.

and the ensuing

of useful

of a single

as the equivalent

cycle of Fig.

serve

promotion

mechanism

as well.

hydrolysis thus

to phosphorylation.

general

here

operation

potential

current energy

apply

reverse

transfer

postulated

should

by the

Since

BIOCHEMICAL AND BIOPHYSICALRESEARCHCOMMUNICATIONS

process.

as much the coupling

(counterclockwise than

the coupling

(counterclockwise

of cycle

1).

REFERENCE Bieber,

T. I.,

Biochem.

Biophys.

Res.

296

Comm.,

-16,

501 (1964).