What is "side chain"

Side \Side\, a.

1. Of or pertaining to a side, or the sides; being on the side, or toward the side; lateral.

   One mighty squadron with a side wind sped.
   --Dryden.

2. Hence, indirect; oblique; collateral; incidental; as, a side issue; a side view or remark.

   The law hath no side respect to their persons.
   --Hooker.

3. [AS. s[=i]d. Cf Side, n.] Long; large; extensive. [Obs. or Scot.] --Shak. His gown had side sleeves down to mid leg. --Laneham. Side action, in breech-loading firearms, a mechanism for operating the breech block, which is moved by a lever that turns sidewise. Side arms, weapons worn at the side, as sword, bayonet, pistols, etc. Side ax, an ax of which the handle is bent to one side. Side-bar rule (Eng. Law.), a rule authorized by the courts to be granted by their officers as a matter of course, without formal application being made to them in open court; -- so called because anciently moved for by the attorneys at side bar, that is, informally. --Burril. Side box, a box or inclosed seat on the side of a theater. To insure a side-box station at half price. --Cowper. Side chain,

   1. one of two safety chains connecting a tender with a locomotive, at the sides.

   2. (Chem.) a chain of atoms attached to the main structure of a large molecule, especially of a polymer. Side cut, a canal or road branching out from the main one. Side dish, one of the dishes subordinate to the main course. Side glance, a glance or brief look to one side. Side hook (Carp.), a notched piece of wood for clamping a board to something, as a bench. Side lever, a working beam of a side-lever engine. Side-lever engine, a marine steam engine having a working beam of each side of the cylinder, near the bottom of the engine, communicating motion to a crank that is above them. Side pipe (Steam Engine), a steam or exhaust pipe connecting the upper and lower steam chests of the cylinder of a beam engine. Side plane, a plane in which the cutting edge of the iron is at the side of the stock. Side posts (Carp.), posts in a truss, usually placed in pairs, each post set at the same distance from the middle of the truss, for supporting the principal rafters, hanging the tiebeam, etc. Side rod.

      1. One of the rods which connect the piston-rod crosshead with the side levers, in a side-lever engine.

      2. See Parallel rod, under Parallel.

         Side screw (Firearms), one of the screws by which the lock is secured to the side of a firearm stock.

         Side table, a table placed either against the wall or aside from the principal table.

         Side tool (Mach.), a cutting tool, used in a lathe or planer, having the cutting edge at the side instead of at the point.

         Side wind, a wind from one side; hence, an indirect attack, or indirect means.
         --Wright.

alt. 1 (context chemistry English) in organic chemistry, that part of a molecule attached to some core structure; a radical 2 (context biochemistry English) the variable parts of amino acids that extend from the peptide backbone in proteins; they are referred to as R-groups, which branch off the backbone at the alpha carbon (Cα). n. 1 (context chemistry English) in organic chemistry, that part of a molecule attached to some core structure; a radical 2 (context biochemistry English) the variable parts of amino acids that extend from the peptide backbone in proteins; they are referred to as R-groups, which branch off the backbone at the alpha carbon (Cα).

In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called "main chain" or backbone. A side chain is also known as a pendant chain, but a pendant group (side group) has a different definition.

1. redirect Dynamic range compression#Side-chaining