The connection between the Anti-Wick and Weyl quantization is given for certain class of global symbols, which corresponding pseudodifferential operators act continuously on the space of tempered ultradistributions of Beurling, respectively, of Roumieu type. The largest subspace of ultradistributions is found for which the convolution with the gaussian kernel exist. This gives a way to extend the definition of Anti-Wick quantization for symbols that are not necessarily tempered ultradistributions.The spaces of ultradistributions and ultradistributions with compact support of Beurling and Roumieu type are defined as the strong duals of D (Mp) (U) and E (Mp) (U), resp. D {Mp} (U) and E {Mp} (U). For the properties of these spaces, we refer to [6], [7] and [8]. In the future we will not emphasize the set U when U = R d . Also, the common notation for the symbols (M p ) and {M p } will be *.For f ∈ L 1 , its Fourier transform is defined byBy R is denoted a set of positive sequences which monotonically increases to infinity. For (r p ) ∈ R, consider the sequence N 0 = 1, N p = M p p j=1 r j , p ∈ Z + . One easily sees that this sequence satisfies (M.1) and (M.3) ′ and its associated function will be denoted by N rp (ρ), i.e. N rp (ρ) = sup p∈N log + ρ p M p p j=1 r j , ρ > 0. Note, for given (r p ) and every k > 0 there is ρ 0 > 0 such that N rp (ρ) ≤ M(kρ), for ρ > ρ 0 . In [8] it is proven that for each K ⊂⊂ R d , the topology of D {Mp} K = lim −→ h→∞ D {Mp},h K is generated by the seminorms p (t j ),K (ϕ) = sup α∈N d D α ϕ L ∞