The paper, "The Determination of Enzyme Dissociation Constants," was authored by Hans Lineweaver and Dean Burk, working at a Department of Agriculture laboratory in Washington, D.C. [J. Am. Chem. Soc., 56, 658 (1934)]. When it was published, Lineweaver was a 26-year-old graduate student who had snagged a job as a laboratory assistant under Burk, a 30-year-old scientist with a Ph.D. in plant nutrition and chemistry.

Lineweaver, who is now 95 years old and retired, tells C&EN that he was mathematically inclined and came up with a more convenient way to plot experimental enzyme kinetic data. The usual plot of the Michaelis-Menten equation, which relates the initial velocity V₀ of an enzyme reaction with the initial substrate concentration, [S], gives a hyperbolic curve, which is hard to draw. Lineweaver performed some simple algebraic operations on the Michaelis-Menten equation

to transform it into what is now known as the Lineweaver-Burk equation:

For enzymes that obey the Michaelis-Menten relationship, a plot of 1/V₀ versus 1/[S]--the so-called double-reciprocal plot--yields a straight line, from which one can obtain more accurate values for the Michaelis constant, K_m, and the maximum velocity, V_max.

Lineweaver showed his boss the new plot, and Burk immediately saw its value, according to Lineweaver. They submitted a paper on the plot, but the referees "were opposed to its publication in JACS for a variety of reasons [that nowadays] make entertaining reading," Burk wrote in a 1984 commentary. Some of the reviewers considered the paper "just a mathematical exercise and not really chemistry at all," Lineweaver recalls.

Nevertheless, the double-reciprocal plot is now enshrined in biochemistry textbooks around the world. And it is "used by almost everyone for initial examination of their kinetic data," says biochemistry professor W. Wallace Cleland of the University of Wisconsin, Madison. "We plot our data this way to see what they look like. Then, on the basis of the patterns, we fit the data to an appropriate rate equation using computer programs."

Joseph S. Fruton, a professor emeritus of biochemistry at Yale University, was aware of the Lineweaver-Burk paper when it appeared in 1934, the year he received his doctorate. "It was useful, but not earthshaking," he tells C&EN. That it's the most highly cited JACS paper "just proves that the frequency of citation is not an adequate measure of scientific importance," he adds.

Indeed, Cleland points out, "methods papers get the most citations. Nowadays, we do not cite papers like this, but many people who are not professional kineticists continue to do so."

In a 1985 commentary, Lineweaver was characteristically humble about his contribution: "Why the many citations? The paper revealed no new fundamental concepts or profound results. It did describe, with examples, a simple treatment of enzyme kinetic data that yielded straight-line plots if the data are consistent with a postulated mechanism, and these can be extrapolated easily to yield characterizing constants of the enzyme. ... It was perhaps serendipity that the paper was timely, having appeared just after interest in enzyme research was increased by the Nobel Prize-winning proof of John H. Northrop, Wendell M. Stanley, and James B. Sumner that enzymes are proteins rather than some phantom substance."

Lineweaver went on to obtain his Ph.D. in 1936 from Johns Hopkins University. "Then I got a better job," he says, although he continued working for USDA until he retired.

Burk later became a leading authority on photosynthesis, receiving the American Chemical Society's Hillebrand Prize in 1952 for his work in this area. During more than 30 years at the National Cancer Institute, he made important contributions to other areas of biochemistry, including cancer research. In his later years, Burk became caught up in the controversy over a link between fluoridation and cancer. He died in 1988 at the age of 84.

C&EN is celebrating the 125th volume of the Journal of the American Chemical Society by featuring selected papers from among its 125 most cited. This paper is number one in citations.