March 15, 2007 at 8:26 pm #7177
What is the size of an antibody, I am trying to figure this out.
March 16, 2007 at 2:20 am #70045
The size? 😕
I don’t get you point, I need the full context of it, thus maybe I could help you 😉
March 16, 2007 at 6:44 am #70057
an antibody is a molecule, it has a size, I want to know what it is…
my really problem is understanding how a bacteria (for example) of size up to 300 µm (if I have my facts correct) can be connected to one another by a molecule which is relatively tiny – the anti body. that is why I want to know the size of antibodies.
March 16, 2007 at 11:39 am #70070
Well, the size could be molecule weight or else.
March 16, 2007 at 3:03 pm #70074CaspaseParticipant
Weird question. Is this in relation to a western blot or something??
I guess the size of an antibody depends on the amount of amino acids and sugar chains on them. I have never seen an exact amount because this is somewhat dynamic.
I would guess around 1,000-1,500 amino acids + sugar.
To ask the question in um I don’t really know…
March 16, 2007 at 3:06 pm #70075
I’ll be satisfied with molecular weight but I would rather know the size in micro/nano meters
March 16, 2007 at 4:39 pm #70077LilKimParticipantquote Paragonidae:
Yes, you are correct, AB’s are much smaller than their targets however AB function in 3 ways.
1. Numberous AB will bind a pathogen all over (opsonization) which triggers a immune response .. in which phagocytic cells well be "target" to this pathogen covered in AB.
2. AB can bind and block at a specific antigen site, thereby blockin/inhibiting function of the target. (then size doesn’t matter)
3. Numberous AB’s can bind forming almost like a web-like strucutre that can essentially "trap" several antigens at once.
.. i’m sure there are other ways that AB’s perform their tasks… but this is all I can think of at the moment.
March 16, 2007 at 6:33 pm #70080
regarding 1st answer: well that is also unclear since for opsonization to occur the pathogen covered with AB must adhere to the phagocyte via fc receptors on the phgo’ (is this correct?) then again the question of size comes up.
though I thank you for your answer I still am in great "need" to know their size… :o)
regarding 3rd: this is new info for me since I know that IgA can for dimers and IgM can for pentamers but I didn’t know that more than that…
I read somewhere (can not remember where) that they can actually cause damage to the pathogens
don’t forget the complement activation via classical pathway.
March 16, 2007 at 6:52 pm #70083LilKimParticipant
As far as the 1st point: Once AB are attached to an antigen… it is essentially "marked" for phagocytosis by a phagocytic cell. Macrophages can therefore associate with the AB constant reagion by the FC receptor… which potently induces phagocytosis.
3rd point: Remember each antibody has (at least) 2 antigen binding sites, so, theoretically it can interact with 2 different antigens at the same time … if you keep this notion in mind and add a few more antibodies and a few more pathogens you can imagine a ‘clump’ of cells with fewer Ab’s in comparision to antigens.
but despite it all… I don’t know the sizes, and I’m not sure why size is exactly relevant….. could you please let me kow why you’re so curious about size? (i’m curious)
March 16, 2007 at 8:15 pm #70087CaspaseParticipant
The root of your question would help us answer it.
Antibodies have variable regions so size is not constant.
The wiki states that when antibodies are digested by papain 2 50 kDa Fab fragments and 1 50 kDa Fc fragment are obtained.
April 6, 2007 at 2:45 am #70897angelsmileParticipant
Antibody is generally a kind of protein,and is it measured by Da or kDa?
April 6, 2007 at 12:26 pm #70912
April 6, 2007 at 12:37 pm #70913blcr11Participant
The crystal structures of antibodies are known. I haven’t looked it/them up, but they have to be in the range of 40-50 angstroms in the shortest dimension to something like 150-200 angstroms in the largest–so say a "box of 50 x 50 x 200 angstroms might be a reasonable guess for the "size" of an antibody.
That would be an IgG. IgMs would be larger. A single IgG molecule is much smaller than a bacterium, but the surface of the bacterium gets coated with many such molecules which acts either to agglutinate the bacterium directly, or attract things like macrophages or eosinophils or leukocytes.
July 22, 2016 at 3:36 pm #116057tmerdolParticipant
I also want to learn the size, because some materials are used as nanoparticles in foods for preservation, enrichment or else, I am worried if they are dangerous for body to circulate in the blood. Producers claim that nanoparticuls are as tiny as antibody which body is used to…
April 27, 2017 at 11:34 am #116207stefangruenertParticipant
If I understand you well you are concerned with the properies of Ig to crosslink pathogens, which can be comparatively large structures like bacteria with sizes exceeding 1 micrometer.
THis consideration is actually quite important and there is an interesting paper which deals with the misleading impressions textbook cartoons leave with us, you might want to check: http://www.slas.ac.cn/upload/20130815-4.pdf
Antibodies come in different types for a start, there are the typical Imunoglobulins G, which are made up of 4 polypeptide chains (2 heavy of 450 AA and 2 light of 210 AA) and are about 150 kDa. An IgG is approximately 10 nm high. But there are also IgA (Dimers) and IgM (Pentamers) which are consderably larger.
Referring to your question it is important to note that IGg are mainly to mark pathogens to induce interactions with immunecells, probably throug engaging several receptors on the cell surface. This was pointed out before. However, it is the considerably larger and multivalent IgM which tend to cross link pathogens and inactivate them. These can obviously have a better reach and also more sites to stabilise the crosslink and are probably much more relevant for viruses, as these would be mopped up and could be taken up by immunecells in bulk.
Here is a visualisation of a typical IgG in isolation based on the RCSB-PDB: https://www.youtube.com/watch?v=H4wcy01tmt8
April 27, 2017 at 1:17 pm #116208claudepaParticipant
10 nm length for an antibody means that it is indeed the size of small nanoparticles. I am working in therapeutic research with non biodegradable 7 nm nanoparticles. We look for this size because it can allow elimination by kidney. However it is not easy because they have a tendency to agregate and therefore form bigger nanoparticles. For biodegradable nanoparticles it can be frequently from 50 nm to 300 nm.
June 7, 2018 at 7:04 am #116377ZusayaParticipantquote stefangruenert post_id=173026 time=1493292843 user_id=313632:
Thanks for sharing! I did not really solve the size shift issue.
Instead, I used the Bioanalyzer assay to determine for each antibody the quantity of immunoprecipitated DNA whose size is below 500bp, which is the usual upper limit of size selection during library preparation of ChIP-Seq samples. I repeated the ChIP experiment to be sure to obtain at least 10ng of immunoprecipitated DNA whose size is below 500bp.
August 22, 2018 at 7:29 am #116380ZusayaParticipant
IgG antibodies are large molecules, having a molecular weight of approximately 150 kDa, composed of two different kinds of polypeptide chain. One, of approximately 50 kDa, is termed the heavy or H chain, and the other, of 25 kDa, is termed the light or L chain (Fig.
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