Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Single-molecule stretching shows glycosylation sets tension in the
  hyaluronan-aggrecan bottlebrush   Large bottlebrush complexes formed from the polysaccharide hyaluronan (HA)
and the proteoglycan aggrecan contribute to cartilage compression resistance
and are necessary for healthy joint function. A variety of mechanical forces
act on these complexes in the cartilage extracellular matrix, motivating the
need for a quantitative description which links their structure and mechanical
response. Studies using electron microscopy have imaged the HA-aggrecan brush
but require adsorption to a surface, dramatically altering the complex from its
native conformation. We use magnetic tweezers force spectroscopy to measure
changes in extension and mechanical response of an HA chain as aggrecan
monomers bind and form a bottlebrush. This technique directly measures changes
undergone by a single complex with time and under varying solution conditions.
Upon addition of aggrecan, we find a large swelling effect manifests when the
HA chain is under very low external tension (i.e. stretching forces less than
~1 pN). We use models of force-extension behavior to show that repulsion
between the aggrecans induces an internal tension in the HA chain. Through
reference to theories of bottlebrush polymer behavior, we demonstrate that the
experimental values of internal tension are consistent with a polydisperse
aggrecan population, likely caused by varying degrees of glycosylation. By
enzymatically deglycosylating aggrecan, we show that aggrecan glycosylation is
the structural feature which causes HA stiffening. We then construct a simple
stochastic binding model to show that variable glycosylation leads to a wide
distribution of internal tensions in HA, causing variations in the mechanics at
much longer length-scales. Our results provide a mechanistic picture of how
flexibility and size of HA and aggrecan lead to the brush architecture and
mechanical properties of this important component of cartilage.

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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
1
The categories of this paper are: cs
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: adap-org