With native lignins). Nevertheless, for reduction of W164S CII powerful k3app decreases with respect to native VP were observed (up to 350-fold for the methylated hardwood lignosulfonate). Far more importantly, the previously observed reduction of W164S CII by native softwood lignosulfonate (Fig. 1a, red dashed line) disappeared when the Coumarin-3-carboxylic Acid Protocol Acetylated or methylated samples have been evaluated as W164S substrates (Fig. 1b, c red dashed lines, respectively).Steadystate DL-Tryptophan Technical Information remedy of native lignin with VP and its W164S variantwith the hardwood lignosulfonate, exactly where the k2app and rate-limiting k3app values seasoned ninefold and 125fold decreases, respectively.Transient kinetics of VP and its W164S variant: nonphenolic ligninskobs (s-1)kobs (s-1)The residual reduction of W164S CI and CII within the above experiments may very well be because of the presence of far more effortlessly oxidizable phenolic units. Utilizing NMR after sample acetylation, the lignosulfonate phenolic content was estimatedIn addition towards the above stopped-flow reactions, the impact on the enzymatic therapies was also analyzed by SEC and 2D-NMR spectroscopy through steady-state reactions. Native VP drastically modified the molecular-mass distribution and main peak (Mp) of softwood and particularly of hardwood lignosulfonates (green continuous lines in Fig. 3a, b, respectively), with respect towards the controls (red and blue lines), revealing a clear polymerizationS zJim ez et al. Biotechnol Biofuels (2016) 9:Web page four ofTable 1 CI reduction constants by acetylated, methylated and native (softwood and hardwood) lignosulfonates: Native VP vs W164S variantSoftwood lignin Acetylated Native VP k2 (s-1) KD2 (M) k2app (s-1 mM-1) W164S variant k2 (s-1) KD2 (M) k2app (s-1 mM-1) 111 19 35.7 3.5 101 8 eight.9 two.7 2080 80 627 87 25.9 1.9 289 22 91 13 66 17 eight.four 0.9 38 3 188 7 Methylated Native Hardwood lignin Acetylated Methylated Native320 24 60 128 19 12 4950 190 540 25 355 122 11 65 7.9 0.Table 2 CII reduction constants by acetylated, methylated and native (softwood and hardwood) lignosulfonates: Native VP vs W164S variantSoftwood lignin Acetylated Native VP k3 (s-1) KD3 (M) k3app (s-1 mM-1) W164S variant k3 (s-1) KD3 (M) k3app (s-1 mM-1) 14.4 0.four 599 31 9.0 0.eight 24.1 1.9 21.two two.0 144 ten 3.0 0.3 147 25 48 2 143 19 12.two 0.5 592 52 20.6 2.five 18.four 1.6 82 five 0.23 0.07 226 33 14 1 14 2 Methylated Native Hardwood lignin Acetylated Methylated Native340 30 96 990 80 8 0.98.two 22.five 16 1.6 0.tendency inside the latter case (Mp of 20,000 Da compared with 5500 Da within the manage) along with the disappearance of a broad shoulder about 11 mL elution volume ( 6800 Da) within the former case. Far more importantly, the W164S variant only brought on a very restricted modification in the molecularmass distribution from the two lignins, in agreement with its low kinetic constants for rate-limiting CII reduction. Such modification integrated a modest displacement of Mp (to 6500 Da) in hardwood lignosulfonate along with a slight reduce from the softwood lignosulfonate shoulder (dashed lines). Then, the structural modifications of guaiacyl (G) and syringyl-guaiacyl (S ) lignins from softwood and hardwood, respectively, had been analyzed by 2D-NMR (Fig. four). The key lignosulfonate units and side-chain interunit linkages are shown in Fig. 4g (no p-hydroxyphenyl units had been detected). Both sulfonated (A) and non-sulfonated (A) -O-4 substructures have been located in the manage lignins, together with less abundant (non-sulfonated) phenylcoumaran (B) and resinol (C) substructures (Fig. 4a, d). After 24-h treat.
