A novel phosphorylation-dependent inhibitory protein (IP) of porcine aorta myosin light chain phosphatase (PA-MLCP) was purified to homogeneity from porcine aorta media. The molecular mass of IP was 20 kDa. IP phosphorylated by endogenous potentiating kinase (IP-K) inhibited not only PA-MLCP activity, but also that of the catalytic subunit of protein phosphatase-1. The amino acid sequence of a peptide derived from IP phosphorylated with IP-K, RHARVT*VK, shared one of the consensus sequences phosphorylatable by protein kinase C (PKC), where T* was phosphorylated. IP was phosphorylated by PKC and the phosphorylated product inhibited PA-MLCP as strongly as IP phosphorylated with IP-K.
The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns of deuterium chemistry in protoplanetary disks is therefore useful for probing how material is inherited or reprocessed throughout the stages of star and planet formation. We present ALMA observations at ∼ 0.
We study the influence of the turbulent transport on ice chemistry in protoplanetary disks, focusing on carbon and nitrogen bearing molecules. Chemical rate equations are solved with the diffusion term, mimicking the turbulent mixing in the vertical direction. Turbulence can bring ice-coated dust grains from the midplane to the warm irradiated disk surface, and the ice mantles are reprocessed by photoreactions, thermal desorption, and surface reactions. The upward transport decreases the abundance of methanol and ammonia ices at r 30 AU, because warm dust temperature prohibits their reformation on grain surfaces. This reprocessing could explain the smaller abundances of carbon and nitrogen bearing molecules in cometary coma than those in low-mass protostellar envelopes. We also show the effect of mixing on the synthesis of complex organic molecules (COMs) are two ways: (1) transport of ices from the midplane to the disk surface and (2) transport of atomic hydrogen from the surface to the midplane. The former enhances the COMs formation in the disk surface, while the latter suppresses it in the midplane. Then, when mixing is strong, COMs are predominantly formed in the disk surface, while their parent molecules are (re)formed in the midplane. This cycle expands the COMs distribution both vertically and radially outward compared with that in the non-turbulent model. We derive the timescale of the sink mechanism by which CO and N 2 are converted to less volatile molecules to be depleted from the gas phase, and find that the vertical mixing suppresses this mechanism in the inner disks.
Here we present high-resolution (15-24 au) observations of CO isotopologue lines from the Molecules with ALMA on Planet-forming Scales (MAPS) ALMA Large Program. Our analysis employs observations of the (J = 2-1) and (1-0) lines of 13 CO and C 18 O and the (J = 1-0) line of C 17 O for five protoplanetary disks. We retrieve CO gas density distributions, using three independent methods: (1) a thermochemical modeling framework based on the CO data, the broadband spectral energy distribution, and the millimeter continuum emission; (2) an empirical temperature distribution based on optically thick CO lines; and (3) a direct fit to the C 17 O hyperfine lines. Results from these methods generally show excellent agreement. The CO gas column density profiles of the five disks show significant variations in the absolute value and the radial shape. Assuming a gas-to-dust mass ratio of 100, all five disks have a global CO-to-H 2 abundance 10-100 times lower than the interstellar medium ratio. The CO gas distributions between 150 and 400 au match well with models of viscous disks, supporting the longstanding theory. CO gas gaps appear to be correlated with continuum gap locations, but some deep continuum gaps do not have corresponding CO gaps. The relative depths of CO and dust gaps are generally consistent with predictions of planet-disk interactions, but some CO gaps are 5-10 times shallower than predictions based on dust gaps. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.
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