THE CHEMICAL WORLD THIS WEEK
The formation of ATP by System II and System I is called photophosphorylation, a process that Dr. Arnon and his coworkers discovered in 1954. Dr. Knaff and Dr. Arnon build their case for the revised picture of the photosynthesis mechanism on a series of carefully executed experiments that they carried out on chloroplasts which they had isolated from several species of plants. They exposed the chloroplasts, suspended in buffer solutions, to strong beams of monochromatic light and measured the ensuing absorbance changes by means of sensitive spectrophotometric techniques. It was the photooxidation of reduced cytochrome b559—so called because it has a characteristic absorbance peak at 5590 A.—that led Dr. Knaff and Dr. Arnon to suspect the existence of a second step in the electron transport network of System II. The half-volt differential between the redox potential of cytochrome b 5 5 9 (0.33 volt) and that of water (0.82 volt) makes it highly improbable that the same primary photochemical reaction involves both these substances, they reasoned. A more likely possibility would be for System II to include a second light-driven reaction that would generate a stronger oxidant capable of extracting electrons from water to produce oxygen. The acceptor of these electrons would be the reductant of cytochrome b 5 5 9 . The existence of C550 became evident when the chloroplasts showed a decrease in light absorbance at 5500 A. that was separate from similar absorption changes characteristic of cytochromes. The UC scientists substantiated the involvement of C550 in the light-induced transport of electrons from water by pretreating the chloroplasts with N-tris (hydroxymethyl)aminomethane(Tris). This treatment is known to decrease the flow of electrons from water into the photosynthetic process, and so would be expected to diminish the absorbance change of C550. "This is exactly what we found," they note. Moreover, when a substitute electron donor, benzidine, is added to the Tris-treated chloroplasts, the magnitude of the C550 absorbance change is restored.
HEW:
No More Witches The Department of Health, Education, and Welfare has rung in the New Year by putting an end to a widely deplored practice dating back to the McCarthyinspired witch-hunting days of the 1950's—blacklisting of scientific advisers.
After extensively examining HEW's security procedures, their constitutionality, and the arguments pro and con, Columbia's Mr. Ellis comes to the conclusion that H E W does have the right to exclude prospective advisers and consultants in its own "self-interest" and for loyalty and suitability reasons. But he argues that these reasons for exclusion should be based on two criteria. One is whether the prospective appointee, as an active member of an organization or as an individual, advocates the violent overthrow of the Government and specifically intends to carry out this objective. The other criterion is whether the candidate's personal traits would adversely affect his job performance or the overall efficiency of the agency that would be employing him.
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HEW's Finch Long-overdue updating
AWARDS: Ten days ago, H E W Secretary Robert Finch announced his approval of revised procedures for selecting and appointing part-time advisers and consultants assisting the department in "nonsensitive areas." Among those affected by the policy change are scientists, including chemists, who are to be chosen to serve on panels of the National Institutes of Health and other H E W agencies. Secretary Finch's announcement follows several months of study by H. Reed Ellis of Columbia University, long-standing criticism by the scientific community, and recent examinations of the need for change by the daily and scientific press (C&EN, Oct. 20, 1969, page 14). Late last fall, H E W asked all its agencies to ensure that there will be no blacklisting. The most recent action is "the first step in a long-overdue updating of our appointment procedures," according to Secretary Finch. Specifically, H E W will: • Replace preappointment investigations for loyalty made through its Office of Internal Security with the requirement that the individual execute an appointment affidavit subject to a postappointment "veracity check" now done for all federal government employees. • Transfer responsibility for evaluating prospective advisers and consultants to agencies such as NIH. • Make appointments "on the basis of professional competence, that is, integrity, judgment, and ability." • Give the individual scientist the opportunity to challenge evidence by an agency that suggests he "possesses traits that would so adversely affect the performance of his job as to disqualify him."
Medal of Science
Brown
Huebner
Awards for distinguished achievement
A chemist—Dr. Herbert C. Brown—was among six scientists named last week by President Nixon as 1969 winners of the National Medal of Science. The medal is the Federal Government's highest award for distinguished achievement in science, mathematics, and engineering. Dr. Brown, professor of chemistry at Purdue University, was cited "for discovery and exploration of the hydroboration reaction and for developing it into a major and powerful tool in chemical synthesis." The reaction has been described as "the most important synthetic process developed in the past three decades." In the field of borohydride chemistry, Dr. Brown's achievements include discovery of a simple route to the production of diborane, discovery of practical syntheses of alkali metal hydrides, and application of borohydrides and aluminohydrides as selective reducing agents for organic compounds. Additionally, he discovered hydroboration of olefins and applied the method to synthesis of primary alcohols from olefins. Besides his accomplishments in boJAN. 12, 1970 C&EN
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