Identification of a thiamin-dependent synthase in Escherichia coli required for the formation of the 1-deoxy-d-xylulose 5-phosphate precursor to isoprenoids, thiamin, and���pyridoxol

In Escherichia coli, 1-deoxy-d-xylulose (or its 5-phosphate, DXP) is the biosynthetic precursor to isopentenyl diphosphate [Broers, S. T. J. (1994) Dissertation (Eidgenössische Technische Hochschule, Zürich)], thiamin, and pyridoxol [Himmeldirk, K., Kennedy, I. A., Hill, R. E., Sayer, B. G. & Spenser, I. D. (1996) Chem. Commun. 1187–1188]. Here we show that an open reading frame at 9 min on the chromosomal map of E. coli encodes an enzyme (deoxyxylulose-5-phosphate synthase, DXP synthase) that catalyzes a thiamin diphosphate-dependent acyloin condensation reaction between C atoms 2 and 3 of pyruvate and glyceraldehyde 3-phosphate to yield DXP. We have cloned and overexpressed the gene (dxs), and the enzyme was purified 17-fold to a specific activity of 0.85 unit/mg of protein. The reaction catalyzed by DXP synthase yielded exclusively DXP, which was characterized by 1H and 31P NMR spectroscopy. Although DXP synthase of E. coli shows sequence similarity to both transketolases and the E1 subunit of pyruvate dehydrogenase, it is a member of a distinct protein family, and putative DXP synthase sequences appear to be widespread in bacteria and plant chloroplasts.

Reductive electrochemical formation of 6H-dibenzo[b,d]pyran-6-one and 2-benzopyran-1(1H)-one

In the present Letter several carbolactones (oxidative products) are obtained under aprotic cathodic conditions in the preparative scaled electrolysis of 1,2-quinones in a divided electrochemical cell and in the presence of oxygen. When 9,10-phenanthrenequinone is reduced 6H-dibenzo[b,d]pyran-6-one and [1,1′-biphenyl]-2,2′-dicarboxylic acid are obtained as major products. In the reduction of 1,2-naphthoquinone, 2-benzopyran-1(1H)-one, and 2-(2-carboxyethenyl)-benzoic acid were formed as main products. The proposed mechanism to explain the formation of these and other products, that involves an electron-transfer reaction to the oxygen in air, is now discussed.

Some account of a paper call'd the Telltale, begun in colledge Sept 1721

The small leather-bound volume holds two sections, a manuscript student periodical, and written tête-bêche, an exchange on smallpox inoculation followed by notes on the rules and activities of a Harvard College student club. The volume begins with thirteen numbered manuscript issues, written in one hand, of the Tell-Tale running from September 9, 1721 to November 1, 1721. Prefaced, "This paper was entitl'd the Telltale or Criticisms on the Conversation & Beheavour of Scholars to promote right reasoning & good manner," the work is modeled after literary periodicals of the time, including the "Spectator," and is considered the oldest student publication at Harvard. The periodical appears to have circulated in manuscript form. The content varies in format and includes letters between Telltale and correspondents, short essays, and advertisements. Topics discussed include conversation, detraction, and flattery. While not specifically about Harvard it does provide some information about the College including evidence of various student activities and organizations at Harvard in the 1720s. The entry explaining the rules of the Telltale Club is heavily faded and nearly illegible. The Telltale records multiple dreams, which are populated by various characters, such as “beautiful” Kate, two “learned Physicians” debating inoculation, “four Fellows” “pushing and shoving one another,” and a “person of a very Dark & swarthy complexion in a Slovenly Dress with 7 patches & 5 sparks on his Face.”

Battle of Prestonpans, Highlands of Scotland, United Kingdom, 1745 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: An exact plan of His Majesty's great roads through the Highlands of Scotland, And. Rutherfurd delin. ; C. Mosley sculp. It was published in 1745. Scale [ca. 1:300,000].The image inside the map neatline is georeferenced to the surface of the earth and fit to the Europe Lambert Conformal Conic coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, cities and other human settlements, roads, selected buildings, shoreline features, fortification, troop dispositions of Jacobite and the Royal Government's troops for the Battle of Prestonpans, 1745, and more. Relief shown pictorially. Includes inset: Plan of the Battle of Preston fought 21 Sept. 1745. The inset is oriented with south at the top and the entire inset map, including text, is at right angles to the main map.This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of originators, ground condition dates, scales, and map purposes.

Battle of Cold Harbor, Virginia and vicinity, 1864 (Raster Image)

This layer is a georeferenced raster image of the untitled historic paper manuscript map: [Map of the Battle of Cold Harbor, Virginia and vicinity]. Scale not given. Covers a portion of Hanover County, Virginia, showing features in the region surrounding the Cold Harbor Battlefield, Virginia, 1864. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Virginia State Plane South Coordinate System (in Meters) (Fipszone 4502). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, or other information associated with the principal map. This map shows features such as roads, towns and villages, drainage, dwellings with names of inhabitants, troop locations with dates, and more. This layer is part of a selection of digitally scanned and georeferenced historic maps of the Civil War from the Harvard Map Collection. Many items from this selection are from a collection of maps deposited by the Military Order of the Loyal Legion of the United States Commandery of the State of Massachusetts (MOLLUS) in the Harvard Map Collection in 1938. These maps typically portray both natural and manmade features, in particular showing places of military importance. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

Battle of Quebec, Canada, 1759 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: Plan of the military & naval operation under the command of the immortal Wolfe, & vice admiral Saunders, before Quebec, J. Wyld, Sculp. ; Alfred Hawkins. It was published by Jas. Wyld, May 1, 1841. Scale [ca. 1:23,700]. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Universal Transverse Mercator (UTM) Zone 19N NAD 1983 coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, drainage, built-up areas and selected buildings, fortifications, troop and ship dispositions and places of military interest for the Battle of Quebec, 1759, and more. Relief is shown by hachures. Includes indexes, notes, tables, views, and inset: Detail of the action fought on the plains of Abraham Septr. 13th. 1759. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.