28 resultados para Steroid 21-hydroxylase

em Brock University, Canada


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The spatial limits of the active site in the benzylic hydroxylase enzyme of the fungus Mortierella isabellina were investigated. Several molecular probes were used in incubation experiments to determine the acceptability of each compound by this enzyme. The yields of benzylic alcohols provided information on the acceptability of the particular compound into the active site, and the enantiomeric excess values provided information on the "fit" of acceptable substrates. Measurements of the molecular models were made using Cambridge Scientific Computing Inc. CSC Chem 3D Plus modeling program. i The dimensional limits of the aromatic binding pocket of the benzylic hydroxylase were tested using suitably substituted ethyl benzenes. Both the depth (para substituted substrates) and width (ortho and meta substituted substrates) of this region were investigated, with results demonstrating absolute spatial limits in both directions in the plane of the aromatic ring of 7.3 Angstroms for the depth and 7.1 Angstroms for the width. A minimum requirement for the height of this region has also been established at 6.2 Angstroms. The region containing the active oxygen species was also investigated, using a series of alkylphenylmethanes and fused ring systems in indan, 1,2,3,4-tetrahydronaphthalene and benzocycloheptene substrates. A maximum distance of 6.9 Angstroms (including the 1.5 Angstroms from the phenyl substituent to the active center of the heme prosthetic group of the enzyme) has been established extending directly in ii front of the aromatic binding pocket. The other dimensions in this region of the benzylic hydroxylase active site will require further investigation to establish maximum allowable values. An explanation of the stereochemical distributions in the obtained products has also been put forth that correlates well with the experimental observations.

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Two enzyme mechanisms were examined: the 21-dehydroxylation of corticosteroids by the anaerobe Eubacterium l en tum, and the hydroxylation of steroids by fungal cytochrome P450. Deuterium labelling techniques were used to study the enzymic dehydroxylation. Corticosteroids doubly labelled (2H) at the C-21 position were incubated with a culture of Eubacterium lentum. It was found that t he enzymic dehydroxylation proceeded with the loss of one 2H f rom C-21 per molecule of substrate. The kinetic isotope ef fect f or the reaction was found to be k~kD = 2. 28. These results suggest that enzyme/substr ate binding in this case may proceed via t he enol form of the substrate. Also , it appears that this binding is, at least in part, the rate determining step of t he reaction. The hydroxylation of steroids by fungal cytochrome P450 was examined by means of a product study. Steroids with a double bond at the A8 (9), ~( lO ), or ~ (ll) position were synthesized. These steroids were then incubated with fungal strains known to use a cytochrome P450 monooxygenase to hydroxylate at positions allylic to these doubl e bonds. The products formed in these incubations indicated that the double bonds had migrated during allylic hydroxylat ion. This suggests that a carbon centred radical or ion may be an intermediate i n the cytochrome P450 cat alytic cycle.

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Two enzyme mechanisms were investigated: the 21-dehydroxylation of corticosteroids by Eubacterium lentum and the dehalogenation of 4-chlorobenzoic acid by Pseudomonas sp. CBS 3. , Chemical and enzymic methods of reduction of 21-oxo steroids were used to generate C-21-d1 compounds of tetrahydrodeoxycorticosterone, with both predominant stereochemistries. It was found that during the dehydroxylation the pro-S hydrogen at the C-21 position was lost preferentially. This suggests that the enzyme removes the pro-S hydrogen during binding to the active site as the ene-diol. To study the hydrolytic replacement of chlorine by hydroxyl , p-chlorobenzoic acid-d4 was prepared and sent to Germany for an ~ncubation with an enzyme preparation of 4-Chlorobenzo~te Dehalogenase. Results suggests the possible loss of deuterium during the conversion of p-chlorobenzoate to p-hydroxybenzoate, from all four ring positions. Many methods of preparing the control compound p-hydroxybenzoic acid-d4 were investigated.

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Survey map of the Second Welland Canal created by the Welland Canal Company showing south Merritton along the boundary between the Grantham and Thorold Townships. Identified structures associated with the Canal include Locks 19, 20, 21, and 22, Lock Tenders House, and the towing path. The surveyors' measurements and notes can be seen in red and black ink and pencil. Local area landmarks are also identified and include streets and roads (ex. Pine Street and Macadamized Road), J. Brown Cement Mill, W. B. Hendershot Saw Mill, W. Parnall Spoke and Sash Factory, W. Beatty Saw Mill, W. Beatty Tannery, a number of structures (possibly houses) belonging to: Mrs. Aikins, J. Battle, and E. Keefer, and a foundry, smithy, and machine shop (all of which possible belonged to J. Dobbie). Properties and property owners of note are: Concession 10 Lots 9 and 10, W. C. Loan Company, P.H. Ball, and J. Keefer. Two small properties belonging to W. B. Hendershot and W. Beatty exist and are outlined in red. A half acre property reserved for a lock lot exists and is outlined in blue. An additional property reserved for a quarry is also identified, but not outlined.

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Survey map of the Second Welland Canal created by the Welland Canal Company showing the areas in and around Port Colborne. Identified structures associated with the Canal include Lighthouse, Pier Light, Old Lock House, Collector's Office, Harbour Master's House, Canal Boundary, Back Ditch, Reserved Back Ditch, Basin, Light-Keeper's House and Ferry Recess. The surveyors' measurements and notes can be seen in red and black ink and pencil. Local area landmarks and businesses are also identified and include Gordon's Woodyard, Welland Rail Road, Welland Railway Elevator and Proposed Elevator, W.R.R. Flour Shed, Roman Catholic Church, School House, Sandhills, Lake Erie, and the High Water Mark. Streets running parallel to Canal include King St., West St., East St., Queen St., Hamilton St., and the Road Allowance are labelled. Streets running perpendicular to Canal include Kent St., Victoria St., Adelaide St., SugarLoaf St., George St., Alexandrina St., William St., Fort Erie St., Lake Rd., and New Road to Dutch Settlement are also labelled. Property owners and leasers as well as buildings on lots are also idenitified and noted as follows: Adams estate, J. Towhig, J.C. Kerr, Mrs. Hill, S. Cooke, Mrs. Yocum, W.T. Cooke, P. Wintermute, J. Shickluna, William Cooke, J. McChesney, John Beatty, W. Robertson, John Gordon, T. Armstrong, John Harper, George Keefer, Estate of James Black, Thomas Park, N. Higgins, S. Hopkins, and L.G. Cartier. Map of the Village of Port Colborne. Being Lot No. 27 and part of Lot No. 28 in the 1st Con. Township of HUMBERSTONE. Scale 2 Chs. per Inch. land shaded in RED Owned by DEPT. Do. Do. BLUE Sold to the COUNTY of WELLAND

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The Military Monitor was a weekly periodical that was published every Monday. The first issue was printed for August 17, 1812 and is believed to have ceased in 1814, as the last issue located was April 2, 1814. The periodical was suspended with the November 23, 1812 issue and resumed with the December 14, 1812 issue. The quote at the top of the first page is "The public good our end". The periodical's various authors included: Desnoues, Joseph, 1794?-1837. O'Connor, Thomas, 1770-1855. Hardcastle, John, 1778?-1835. Van Pelt, Peter, 1779?-1843. Wall, Stephen. Van Riper, Nicholas. Other authors are believed to be the American Antiquarian Society. Proprietors: T. O'Connor and S. Wall, 1812; T. O'Connor, 1812- . Printers: Hardcastle and Van Pelt, for T. O'Connor and S. Wall, Sept. 14-Oct. 5, 1812; J. Desnoues, Oct. 12, 1812- ; N. Van Riper, Nov. 6, 1813- . This issue was included in a bound volume of the Military Monitor and American Register. Other Dates included are: 1812 August 31 1812 December 14 1812 November 23 1812 October 12 1812 October 19 1813 April 5 1813 April 12 1813 April 26 1813 February 1 1813 January 11 1813 March 29

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The Weekly Register, also known as Niles Weekly Register, was a weekly periodical edited by Hezekiah Niles (1777-1839) and published in Baltimore Maryland. Volumes of interest were published between 1811 (Vol. 1, No. 1, September 7, 1811) to 1814 (Vol. 5, No. 26, February 26, 1814). These volumes focus primarily on 19th century politics and government in the United States of America. Niles edited and published the Weekly Register until 1836, making it one of the most widely-circulated magazines in the United States. The popularity also made Niles into one of the most influential journalists of his day. Devoted primarily to politics, Niles' Weekly Register is considered an important source for the history of the period. The Register also recorded current economics, technology, science, medicine, geography, archaeology, the weather, and stories of human interest. This issue is part of a bound book titled the Weekly Register 1812-1814. Pages are divided as follows: November 14, 1812- Pages 161-174 January 22, 1814- Pages 337-352 July 30, 1814- Pages 361-376 Look for other issues of the Weekly Register within the website.

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Volumes of interest were published between 1812 and 1815 with articles about the War of 1812.

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Volumes of interest were published between 1812 and 1815 with articles about the War of 1812. Issue for Feb. 21, 1815, beginning on page 2 and continuing to take all of page 3 and some of page 4 is the full text headed: "TREATY OF PEACE" which is prefaced with an address by James Madison. Also in this issue is an article: "Victory At Orleans" and another article headed: "The War--From New Orleans".

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Volumes of interest were published between 1812 and 1815 with articles about the War of 1812.

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Volumes of interest were published between 1812 and 1815 with articles about the War of 1812.

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