TABLE 1.

Band assignments

Wavenumber value (cm−1)	Assignmenta	Comments
∼1,735	νC⩵O of ester functional groups primarily from lipids, fatty acids, and PHB (18, 40, 45)b	Exact position of PHB absorbance depends on the degree of crystallinity of the PHB
∼1,650	νC⩵O of amides associated with proteins (29, 40)	Usually called the amide I band; may also contain contributions from C⩵C stretches of olefinic and aromatic compounds
∼1,540	δ(N H) of amides associated with proteins (29, 40)	Usually called the amide II band; may also contain contributions from C⩵N stretches
∼1,455	δas (CH3) and δas (CH2) of proteins (44)	Positions of these assignments can vary; contributions also from PHB
∼1,398	δs (CH3) and δs (CH2) of proteins, νs(C O of COO−) groups (29, 44)	Positions of these assignments can vary; contributions also from PHB
∼1,242	νas (P⩵O) of the phosphodiester backbone of nucleic acids (DNA and RNA) (29, 41)	May also be due to the presence of phosphorylated proteins and polyphosphate storage products
∼1,080	νs (P⩵O) of the phosphodiester backbone of nucleic acids (DNA and RNA) (29, 41)	May also be due to the presence of phosphorylated proteins and polyphosphate storage products
1,200–900	ν(C O C) of polysaccharides (41, 44)	Contributions also from PHB

^aν_as, asymmetric stretch; ν_s, symmetric stretch; δ_as, asymmetric deformation (bend); δ_s, symmetric deformation (bend). 

^bThe numbers in parentheses are reference numbers.