IgM, unlike other heavy chain isotypes, appears in the serum as a pentamer of the basic...

90.2K

Verified Solution

Question

Biology

IgM, unlike other heavy chain isotypes, appears in the serum asa pentamer of the basic four-chain Ig monomer; thus making itdecavalent rather than bivalent in terms of combining sites. Oneintriguing result of this is an increase in the likelihood - allother things being equal - that the IgM will be bound (versusfree). Another way of saying this is that even though the affinityconstant (Ka) of each individual combining site is the sameregardless of the overall molecule's valency, this decavalentversion will have more whole Ig molecules bound (to antigen) atequilibrium than would a bivalent version (given equimolar levelsof combining sites). This phenomenon is sometimes called increased\"avidity\" (to avoid using the rigorously defined chemical term\"affinity\" incorrectly). I'd like you to discuss a few issuesraised by this:
First, bearing in mind that IgM is the first isotype madeduring primary responses,why does this higher \"avidity\" makeintuitive sense?
Second, can you foresee ways that this added \"stickiness\" mightalso engender problems?
Finally, does this mean that IgM molecules are more or less\"specific\" than their IgG counterparts? (watch it, that last one istricky)

Answer & Explanation Solved by verified expert

3.6 Ratings (438 Votes)

At the onset of a recent infection it is always the IgM antibodies that appear first In fact this property of IgM being the primary response to any new infection is used as a serological tool to identify between current and old infections IgM circulates as a pentamer of disulfidelinked immunoglobulin molecules joined by a single crosslinking peptide called J Chain See Answer

Get Answers to Unlimited Questions

Join us to gain access to millions of questions and expert answers. Enjoy exclusive benefits tailored just for you!

Membership Benefits:

Unlimited Question Access with detailed Answers
Zin AI - 3 Million Words
10 Dall-E 3 Images
20 Plot Generations
Conversation with Dialogue Memory
No Ads, Ever!
Access to Our Best AI Platform: Flex AI - Your personal assistant for all your inquiries!

Become a Member