Manipulate and stretch single pectin molecules with modified molecular combing and fluid fixation techniques

Manipulating and stretching single pectin molecules offer convenience to determine the chain lengths and further illustrate the action between pectins and other macromolecules. Pectin molecules on mica surfaces, which were imaged in air with atomic force microscopy (AFM), can be aligned and stretched through applying modified molecular combing and fluid fixation techniques. Modified molecular combing showed more effective and powerful for manipulation than fluid fixation. Chelate-soluble pectin (CSP) can be straightened into line to one direction by molecular combing while sodium carbonate-soluble pectin (SSP) shows 'V' structures. The differences may be the result of the different parts of the pectins which touched the mica surface firstly during the dropping, and the lengths of the chains. CSP was relatively long and initially touched the mica with the end point while SSP was short and touched the mica firstly with its middle part.