# 03 Pyrimidine

## Synthesis

![](https://f001.backblazeb2.com/file/wikiFiles/B76661B9-62C1-49B6-8876-52517E913CC2.jpg)

* create monophosphate version

![](https://f001.backblazeb2.com/file/wikiFiles/F28937F6-3708-44CE-B54F-4ECEEEC0CC2D.jpg)

* II: found in cytosol, rate limiting, inhibited by UMP
* I: in mito, for urea cycle

![](https://f001.backblazeb2.com/file/wikiFiles/A6B9AD91-D759-4B73-9D64-2734522D54C9.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/6362E5ED-BD02-4D71-8B9A-4079B2371D94.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/3AF9EB02-4CF3-4321-87BE-B58573579533.jpg)

* bifunction: catalyzes 2 steps

![](https://f001.backblazeb2.com/file/wikiFiles/BA9F6192-FC4B-498D-9C5C-F210231E8820.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/E3736DB3-BAEE-4431-9227-37BE3CA0301D.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/DA4C5FF0-F1DE-40A1-90FA-9768C7385F24.jpg)

* hypersegmented neutrophils
* letter U: orotic acid in Urine, Ump synthase, Uridine treatment

![](https://f001.backblazeb2.com/file/wikiFiles/8C505C58-8900-4962-9940-2924AFE9C665.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/C6552811-6B69-4BE6-B599-0E0090D554E6.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/3D83997C-280B-4FF8-985A-F7CA355B60A3.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/4C066ED0-204F-480B-9820-A753BB81118B.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/B8F072F1-71D1-4111-A3A5-32ECFFE7BF7E.jpg)

## Thymidine

![](https://f001.backblazeb2.com/file/wikiFiles/C8B387BB-176E-4C3C-8AE5-D93F841A21EA.jpg)

* adding methyl group to create thymidine

![](https://f001.backblazeb2.com/file/wikiFiles/B7EA7FAE-9697-45F2-BFE5-6CBEE1EB35F7.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/68598C05-98C6-4294-9F8F-68AD513B9F34.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/DBBFEF8C-E978-4B39-BE5F-9D43771A80C3.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/29CD4CFD-1671-4DA0-8F2A-E66B4C9EF3BD.jpg)

* folate to THF, add carbon to dUMP

![](https://f001.backblazeb2.com/file/wikiFiles/59F1699E-406B-470C-AC91-E8C5D6845063.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/3174F1E5-6A1A-41AF-8B1D-CE555D6E03BD.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/1C834332-6533-4540-8948-00F930D6E448.jpg)

* donate 1 carbon

![](https://f001.backblazeb2.com/file/wikiFiles/E9169465-2932-47D8-BE0B-039BC8698CE8.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/A5C8D362-D37C-4BFB-B90E-D9C98F42EF58.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/31E32DF7-049D-4951-A418-D5403A335883.jpg)

* humans don't rely on PABA to make folate

![](https://f001.backblazeb2.com/file/wikiFiles/6D48DF17-1A09-46D0-A4A2-3C4C6F6175C5.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/D15E4EE4-C287-4FA0-8B50-C4F2F0198B7F.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/F1BB64DC-1C0D-4667-B834-EB591C198F09.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/B148C29F-0177-445B-8956-9F29ABECB56B.jpg)

* deficient in B12: all folate trapped in N5 methyl THF

![](https://f001.backblazeb2.com/file/wikiFiles/423C7924-8EF4-4367-ABF0-4EF7F7CFFA85.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/BEC954CC-7AF7-418D-8E4F-1A82953373EA.jpg)

* deficient in either folate or B12 leads to high homocysteine level
* MMA: fatty acid conversion

![](https://f001.backblazeb2.com/file/wikiFiles/F308E6A3-2AAC-4F95-AD1C-73C2A9705E0A.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/96890B26-2989-4679-AB42-5097124F1C14.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/849BE2F0-55A8-4CC6-8C16-52BF15878CAA.jpg)


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