Kinetic studies of Escherichia coli and human SAICAR synthetase.

More About This Textbook

Overview

Phosphoribosyl-aminoimidazole-succinocarboxamide synthetase (SAICAR synthetase) catalyzes the eighth step of de novo IMP biosynthesis in bacteria, and the seventh step in humans. The SAICAR synthetase reaction is analogous to that of adenylosuccinate synthetase (first committed step of AMP biosynthesis), using ATP to ligate 5-amino-imidazole-4-carboxy ribonucleotide and L-aspartate to produce 5-aminoimidazole-4(N-succinylcarboxamide) ribonucleotide (SAICAR). SAICAR synthetase and other enzymes of purine nucleotide biosynthesis are targets of natural products that impair cell growth. Prior to these studies, the kinetic mechanism of any SAICAR synthetase was unknown. Herein are reported the kinetic mechanisms of bacterial and human SAICAR synthetase activities, the structure of the bacterial enzyme from Escherichia coli, and substrate recognition properties of both the human and bacterial forms of the enzyme. The human enzyme is bifunctional, combining 5-aminoimidazole ribonucleotide (AIR) carboxylase activity with SAICAR synthetase activity. A determination of the kinetic mechanism of SAICAR synthetase requires the absence of AIR carboxylase activity. A slow, tight-binding inhibitor (4-Nitro-5-aminoimidazole ribonucleotide) and the mutation of a residue critical to catalysis independently eliminated interfering AIR carboxylase activity. The kinetic mechanism of the SAICAR synthesis is the same for the two forms of AIR carboxylase-impaired enzyme, but differences in kinetic parameters demonstrate a linkage mechanism between the two types of active site in the human bifunctional enzyme. Human SAICAR synthetase may impose a metering function that insures constant output of SAICAR over a ten-fold variation in the concentration of CAIR.
Read More Show Less

Product Details

  • BN ID: 2940032607854
  • Publisher: ProQuest LLC
  • Sold by: Barnes & Noble
  • Format: eTextbook
  • Pages: 133

Customer Reviews

Be the first to write a review
( 0 )
Rating Distribution

5 Star

(0)

4 Star

(0)

3 Star

(0)

2 Star

(0)

1 Star

(0)

Your Rating:

Your Name: Create a Pen Name or

Barnes & Noble.com Review Rules

Our reader reviews allow you to share your comments on titles you liked, or didn't, with others. By submitting an online review, you are representing to Barnes & Noble.com that all information contained in your review is original and accurate in all respects, and that the submission of such content by you and the posting of such content by Barnes & Noble.com does not and will not violate the rights of any third party. Please follow the rules below to help ensure that your review can be posted.

Reviews by Our Customers Under the Age of 13

We highly value and respect everyone's opinion concerning the titles we offer. However, we cannot allow persons under the age of 13 to have accounts at BN.com or to post customer reviews. Please see our Terms of Use for more details.

What to exclude from your review:

Please do not write about reviews, commentary, or information posted on the product page. If you see any errors in the information on the product page, please send us an email.

Reviews should not contain any of the following:

  • - HTML tags, profanity, obscenities, vulgarities, or comments that defame anyone
  • - Time-sensitive information such as tour dates, signings, lectures, etc.
  • - Single-word reviews. Other people will read your review to discover why you liked or didn't like the title. Be descriptive.
  • - Comments focusing on the author or that may ruin the ending for others
  • - Phone numbers, addresses, URLs
  • - Pricing and availability information or alternative ordering information
  • - Advertisements or commercial solicitation

Reminder:

  • - By submitting a review, you grant to Barnes & Noble.com and its sublicensees the royalty-free, perpetual, irrevocable right and license to use the review in accordance with the Barnes & Noble.com Terms of Use.
  • - Barnes & Noble.com reserves the right not to post any review -- particularly those that do not follow the terms and conditions of these Rules. Barnes & Noble.com also reserves the right to remove any review at any time without notice.
  • - See Terms of Use for other conditions and disclaimers.
Search for Products You'd Like to Recommend

Recommend other products that relate to your review. Just search for them below and share!

Create a Pen Name

Your Pen Name is your unique identity on BN.com. It will appear on the reviews you write and other website activities. Your Pen Name cannot be edited, changed or deleted once submitted.

 
Your Pen Name can be any combination of alphanumeric characters (plus - and _), and must be at least two characters long.

Continue Anonymously

    If you find inappropriate content, please report it to Barnes & Noble
    Why is this product inappropriate?
    Comments (optional)